Name: Blueberry Lemon Dump Cake
Prep time: 5 min
Cook time: 50 min
Ingredients: 4 cups frozen blueberries (do not thaw); 1 box lemon cake mix (15.25 oz); 1/2 cup 1 stick unsalted butter, melted; 1/2 cup granulated sugar (optional); 1 tablespoon cornstarch (optional); 1 teaspoon vanilla extract (optional); Zest of 1 lemon (optional)

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This blueberry lemon dump cake is an easy, sunshiney dessert for anyone who is done with winter and ready for something a little brighter and more cheerful. That’s what this dessert does for me – it reminds me of spring in the best ways, and it makes me happy because it is SO EASY. It uses frozen blueberries and a lemon cake mix for the easiest spring or summer dessert ever. No mixing bowls, no complicated steps — just layer, bake, and devour.

This is a delicious dessert that looks impressive on the table, sounds impressive to name, but takes just minutes to assemble. Perfect for Easter, Mother’s Day brunch, potlucks, or a simple weeknight treat.

Why You’ll Love This Recipe

Uses frozen blueberries (no need to thaw)
Minimal prep and ingredients you might already have on hand
Sweet, jammy blueberry layer with buttery lemon topping
Tastes like a cross between cobbler and crisp
Perfect with whipped cream or vanilla ice cream
Smells amazing while it’s baking

How to Make Blueberry Lemon Dump Cake

Ingredients

4 cups frozen blueberries
1 lemon cake mix (15.25 oz box)
1 tablespoon cornstarch or flour (optional)
1 teaspoon vanilla extract (optional)
1/2 cup (1 stick) unsalted butter, melted
Zest of 1 lemon (optional but recommended)

Step By Step Directions

1. Preheat Your Oven

Preheat to 350°F and lightly grease a 9×13 baking dish.

2. Make the Blueberry Layer

Add frozen blueberries directly to the baking dish. Sprinkle with cornstarch. Add vanilla extract and gently stir to coat. No need to thaw the berries — they’ll release juices as they bake.

3. Add the Lemon Cake Mix

Sprinkle the dry lemon cake mix evenly over the blueberries. Do not stir.

4. Add Butter

Drizzle melted butter evenly over the cake mix, covering as much of the dry mix as possible. Sprinkle lemon zest over the top for extra brightness.

5. Bake

Bake for 45 to 55 minutes, until the top is golden brown and the blueberry filling is bubbling around the edges. Let cool for 10 to 15 minutes before serving.

Why Is There Cornstarch in This Dump Cake?

If you’ve made classic dump cakes before, you might notice something slightly different here — the cornstarch.

Many traditional dump cake recipes skip a thickener entirely. But this version uses frozen blueberries, which release more liquid as they bake. Without a little help, that extra juice can create a thinner, more syrupy bottom layer.

The small amount of cornstarch helps:

Thicken the blueberry juices as they bubble
Create a jammy, cobbler-style texture
Prevent the bottom from becoming overly runny
Help the dessert hold its shape a bit better when scooped

It doesn’t affect the flavor — it simply improves the texture.

If you prefer a looser, saucier dessert (especially if serving warm in bowls with ice cream), you can leave it out. But if you love that thick, spoonable blueberry layer that sets up nicely as it cools, the cornstarch is worth including.

Tips for the Best Dump Cake

If you see dry patches halfway through baking, lightly drizzle a bit more melted butter over those spots.
For extra texture (or to look extra fancy at brunch), sprinkle 1/4 cup sliced almonds on top before baking.
Want it sweeter? Add 1/2 cup white chocolate chips over the blueberries before adding cake mix.
For a bakery-style finish, dust lightly with powdered sugar before serving.

How to Serve

This dessert is best served warm with:

Vanilla ice cream
Fresh whipped cream
A spoonful of lemon curd
Extra fresh blueberries

It’s also delicious chilled the next morning with coffee – especially if that coffee has a splash of blueberry cobbler simple syrup in it.

Variations

Blueberry Lemon Cream Cheese Dump Cake

Cube 4 oz softened cream cheese and scatter over the blueberries before adding cake mix.

Triple Berry Lemon Dump Cake

Use a mix of frozen blueberries, raspberries, and blackberries.

Gluten Free Version

Use a gluten free lemon cake mix. The rest of the recipe stays the same.

Make Ahead and Storage

Store covered in the refrigerator for up to 4 days.
Reheat individual portions in the microwave for 20 to 30 seconds.
Freeze for up to 2 months.

Frequently Asked Questions

Do I have to use cornstarch?
No. The cake will still bake without it. However, frozen blueberries release a lot of juice, and cornstarch helps thicken that liquid into a jammy filling instead of a thin syrup. If you prefer a looser texture, you can skip it.

Do I need to thaw frozen blueberries first?
No. Add them straight from the freezer. Thawing can make them release even more liquid before baking.

Can I use fresh blueberries?
Yes. Fresh berries release less juice, so you may not need the cornstarch. Baking time may be slightly shorter.

Why is my topping powdery?
The butter likely didn’t fully cover the cake mix. Try drizzling more evenly or slicing thin pats of butter across the top instead of pouring melted butter.

A Bright and Easy Spring Dessert

This blueberry lemon dump cake is one of those dependable, cheerful recipes you’ll come back to again and again. The sweet blueberries and bright lemon cake topping feel fresh and light, especially as we head into spring and summer baking. It is the perfect low effort, high reward dessert. Enjoy!

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