Summer is almost here, and if you’re searching for the perfect seasonal dessert, this Blueberry Crisp Cake is a must-try. Layers of tender oatmeal cake, a bright blueberry compote, crunchy oat crumble, and a silky blueberry buttercream come together for a dessert that tastes like summer in every bite.
With blueberry season in full swing, this cake is destined to be your go-to dessert. Pick up fresh or frozen blueberries, gather the pantry staples, and follow the simple steps below. Once you try it, it may join your list of favorite summer desserts.
For more summer dessert inspiration, try some of my other favorite berry recipes.
Why this recipe works
- Oatmeal cake layers: Cooked old-fashioned oats (not quick or steel-cut) are added to the batter for moistness, texture, and a subtle nutty flavor.
- Blueberry filling: A cooked compote, made with fresh or frozen berries, gives the cake a bright, true blueberry flavor and a spoonable filling for the layers.
- Oat crumble: Like a classic crisp topping, oats and butter form a crunchy element that contrasts with the tender cake and soft filling.
- Blueberry buttercream: Freeze-dried blueberries and a small amount of blueberry emulsion intensify the fruit flavor and natural color in the frosting.
- Versatile format: This recipe is written for a three-layer 8-inch cake but can be adapted to four 6-inch layers, a sheet cake, a 9×13, or cupcakes—see the FAQ and notes for timing adjustments.
Ingredient list
Below are notes on a few key ingredients and why they matter. Refer to the recipe card for the full amounts and complete ingredient list.
- Unsalted butter: Use unsalted so you can control salt levels. For the cake, bring butter to room temperature 2–4 hours in advance.
- Old-fashioned oats: Use old-fashioned oats for texture and structure; quick or steel-cut oats won’t give the same result.
- Light brown sugar: Adds moisture and caramel notes—my preferred sugar for this cake.
- Eggs: Large or extra-large eggs, brought to room temperature 2–4 hours before baking, help create proper texture and lift.
- Cinnamon: Ground cinnamon adds warm depth—this recipe uses it generously for complementing the blueberries.
- Blueberries: Fresh or frozen both work. Save a few for garnish.
- Blueberry emulsion & freeze-dried blueberries: The emulsion concentrates flavor and freeze-dried berries deepen color and taste in the buttercream. Both are optional but recommended for an intense blueberry profile.
Step by Step Instructions — Cake
Step 1: Cook the oats. Bring water to a boil in a medium pot, add 2 cups old-fashioned oats, stir, remove from heat, cover, and let sit 15–20 minutes to absorb the water. Cool fully (about 20 minutes) before adding to the batter.
Step 2: Sift dry ingredients. Whisk together baking soda, salt, cinnamon, baking powder, ½ cup oats, and flour.
Step 3: Cream butter and sugar. In a stand mixer fitted with the paddle, cream butter and light brown sugar on medium until light and fluffy, about 2 minutes.
Step 4: Add eggs and vanilla. With the mixer on medium, add eggs one at a time, scraping the bowl between additions. Add vanilla and mix 30 seconds more.
Step 5: Combine oats and flour mixture. Turn mixer off, add cooled cooked oats and the dry mixture, and mix on low until just combined.
Step 6: Divide and bake. Divide batter evenly into prepared pans (about 20 ounces per 8-inch pan). Bake at 325°F for 28–32 minutes, or until a toothpick shows a few moist crumbs.
Step 7: Cool and level. Cool in pans 10–15 minutes, transfer to wire racks to cool completely, then level if needed before assembling.
Step by step — Blueberry compote
Step 1: Cook berries, sugar, and water. In a small saucepan over medium heat, combine blueberries, granulated sugar, and water. Cook until the berries begin to burst and a sauce forms.
Step 2: Make a slurry. Mix cornstarch with 1/3 cup water to form a slurry.
Step 3: Thicken the compote. When the compote is hot and bubbling gently, add the slurry and stir until it thickens. The color will darken as you cook off the raw cornstarch flavor.
Step 4: Cool. Transfer to a bowl, press plastic wrap onto the surface to prevent a skin, and let it cool to room temperature. It will thicken further as it cools.
Step by Step — Crumble
Step 1: Preheat oven. Preheat to 375°F and line a baking sheet with parchment.
Step 2: Mix and bake. Combine oats, brown sugar, flour, cubed butter, cinnamon, and salt. Mix until clumpy, spread on the sheet, and bake 8–10 minutes, stirring once, until golden.
Step 3: Break up pieces. Cool completely, then break into smaller crumble pieces as needed.
Step by step — Buttercream
Step 1: Beat the butter. Cream slightly chilled butter in a stand mixer for about 2 minutes to soften.
Step 2: Add powdered sugar. With the mixer on low, add sifted powdered sugar in batches until incorporated.
Step 3: Flavor and color. Add pulverized freeze-dried blueberries and blueberry emulsion. Optionally add a small amount of gel color for a deeper hue.
Step 4: Add cream and salt. With the mixer on medium, add heavy cream and a pinch of salt.
Step 5: Whip to finish. Increase to medium-high and beat 4–5 minutes until lighter in texture. Use a spatula to press out any air pockets.
Cake assembly tips
- Work with cold or frozen cake layers to reduce crumbs and keep layers stable.
- Use a small dollop of frosting on your cake board to secure the first layer.
- Pipe a frosting rim around each layer before adding compote to prevent leaking; use about 1/2 cup compote per layer and avoid overfilling.
- Sprinkle crumble between layers for texture.
- Place the final layer top-side down for a flat top, apply a thin crumb coat, freeze 10 minutes, then finish frosting and decorating.
Expert baking tips
Make sure all cake ingredients are at room temperature for even mixing and better rise. You can make the components ahead—bake layers, prepare compote, crumble, and frosting—and assemble the day you plan to serve. Sifting powdered sugar before adding it to the buttercream keeps the frosting smooth and silky. If you want a truer blueberry color, a touch of gel food coloring works well.
FAQ
Can I make this into a sheet cake?
Yes. It adapts well to a sheet cake, four 6-inch layers, or a 9×13 (bake the 9×13 for 40–45 minutes).
Can these be made into cupcakes?
Yes. Reduce baking time to about 23–27 minutes depending on your oven and pan size.
What if I can’t find blueberry emulsion?
If you can’t source emulsion, the frosting still works with extra pulverized freeze-dried blueberry for flavor. Emulsion is optional.
Storing and freezing
If you’re splitting the process across multiple days, bake, cool, level, and wrap cake layers tightly in plastic wrap. Store them in the refrigerator for 3–5 days or freeze for longer storage. For a decorated cake, chill first, then wrap in plastic and an outer layer of foil for long-term freezing—up to 6 months. Thaw in the fridge before serving to reduce condensation.
Recipe
Blueberry Crisp Cake
Molly Murphy
30 mins
30 mins
1 hr
Dessert
Cake
18 people
Ingredients
FOR THE CAKE
- 2 ½ cups water
- 2 cups uncooked old-fashioned oats
- 1 cup unsalted butter, room temperature
- 1 ¾ cups light brown sugar, packed
- 2 teaspoons pure vanilla
- 4 eggs, room temperature
- 1 teaspoon kosher salt
- 1 teaspoon baking powder
- 2 teaspoons baking soda
- 2 teaspoons cinnamon
- 3 cups all-purpose flour
- ½ cup uncooked old-fashioned oats
FOR THE BLUEBERRY COMPOTE
- 2 Tablespoons water
- 1 cup blueberries, fresh or frozen
- ½ cup granulated sugar
- 1 Tablespoon cornstarch
- ⅓ cup water for slurry
FOR THE CRUMBLE
- ¾ cup old-fashioned oats
- ¼ cup light brown sugar, packed
- ¼ cup all-purpose flour
- 3 Tablespoons unsalted butter, cold and cubed
- ½ teaspoon ground cinnamon
- Pinch of salt
FOR THE BLUEBERRY BUTTERCREAM
- 2 cups unsalted butter, slightly chilled
- 5 cups powdered sugar, measured and sifted
- ¼ cup freeze-dried blueberries, pulverized
- ⅓ cup heavy whipping cream
- 2 teaspoons blueberry emulsion (optional)
- Pinch of salt
Instructions
For the cake
- Preheat oven to 325°F. Spray three 8-inch or four 6-inch round cake pans, line bottoms with parchment, and spray again.
- Cook 2 cups oats in boiling water, remove from heat, cover, and let absorb for 15–20 minutes. Cool completely before using.
- Whisk baking soda, salt, cinnamon, baking powder, ½ cup oats, and flour together and set aside.
- Cream butter and brown sugar on medium until light and fluffy, about 2 minutes.
- Add eggs one at a time, scraping the bowl between additions, then add vanilla and mix 30 seconds.
- Fold in cooled cooked oats and the flour mixture on low until just combined.
- Divide batter into prepared pans (about 20 oz per 8-inch pan) and bake 28–32 minutes, or until a toothpick shows a few moist crumbs.
- Cool in pans 10–15 minutes, then transfer to wire racks to cool completely and level if needed.
For the blueberry compote
- Combine blueberries, sugar, and water in a saucepan over medium heat. Cook until berries release juices and a sauce forms.
- Mix cornstarch with ⅓ cup water to make a slurry. Add to the hot compote and stir until it thickens and the color deepens.
- Press plastic wrap on the surface and cool to room temperature; refrigerate to speed cooling if desired.
For the crumble
- Preheat oven to 375°F. Line a baking sheet with parchment.
- Combine oats, brown sugar, flour, cubed butter, cinnamon, and salt. Mix until clumpy, spread on the sheet, and bake 8–10 minutes, stirring once. Cool and break into smaller pieces.
For the blueberry buttercream
- Cream butter about 2 minutes until softened.
- With mixer on low, add sifted powdered sugar in batches.
- Add pulverized freeze-dried blueberries and blueberry emulsion.
- With mixer on medium, add heavy cream and a pinch of salt.
- Beat on medium-high 4–5 minutes until light; use a spatula to remove air pockets.
Assembly
- Pipe a small dollop of frosting onto a cake board and place the first cake layer top-side up.
- Pipe a rim of frosting around the edge to contain the compote, spread about ½ cup compote, and sprinkle with crumble.
- Repeat with the second layer. Place the final layer top-side down.
- Apply a thin crumb coat and freeze 10 minutes. Finish frosting and decorate with remaining buttercream and crumble.
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