Blackberry Crumb Cake

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Last Updated on May 27, 2026 by Kiersten James

This homemade blackberry crumb cake is baked in a 9×13 dish with fresh blackberries and a buttery farmhouse crumble topping.

This blackberry crumb cake is something I love to make during the summer when we have a ton of fresh berries, and I’m not yet at the point of wanting to make jam.

The cake stays soft and buttery, the blackberries bake down throughout the dish, and the crumble on top is the same farmhouse-style topping I use for all of my muffins and quick breads.

I usually bake this in a regular 9×13 glass dish because it feeds a crowd, slices easily, and honestly just makes my life easier.

Adding a glaze on top is optional, but I like it because I think it makes the cake feel a little more finished without adding any unnecessary sweetness.

Why You’ll Love This Blackberry Crumb Cake

• Fresh blackberries create beautiful swirls throughout the cake
• Bakes in a 9×13 glass dish
• Farmhouse crumb topping adds bakery-style texture
• Perfect for brunches, summer gatherings, or coffee tables
• Slices clean and transports well
• Freezes very well

Ingredient Highlights:

Fresh Blackberries: Fresh blackberries bake down into the cake, giving it little pockets of berry flavor without needing pie filling or anything artificial. If it is off-season and you want to use frozen blackberries, thaw them first and make sure they are drained very well.

Sour Cream: Sour cream is what keeps the cake soft and helps the cake stay fresh longer instead of drying out the next day.

Butter: Butter gives the cake a richer flavor and helps it taste like a real homemade coffee cake instead of a boxed mix.

Brown Sugar: Brown sugar adds moisture and gives the crumb topping a warm caramel flavor that works really well with blackberries.

Vanilla: Vanilla rounds out the flavor and keeps the cake from tasting flat. Even a small amount makes a noticeable difference in homemade cakes.

Farmhouse Crumble Topping: This is the same crumble topping I use on my muffins and quick breads. I make it in larger batches, then store it in a container in the refrigerator to add to whatever I’m baking that week.

Powdered Sugar Glaze: This is optional, but it makes the cake feel a little more finished without causing it to become overly sweet.

Tips for the Best Results

How to Make a Fresh Blackberry Crumb Cake

Ingredients:

• 2 1/4 cups all-purpose flour
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1 1/4 cups granulated sugar
• 1 cup butter, softened
• 1 teaspoon vanilla extract
• 2 eggs, room temperature
• 8 oz sour cream

For the Blackberries:

• 1 1/2 cups blackberries, thawed and drained if frozen
• 3 tablespoons granulated sugar
• 1 1/2 teaspoons cinnamon

Farmhouse Crumb Topping:

• 1 cup all-purpose flour, leveled
• 1/4 cup whole wheat flour
• 1/4 cup brown sugar, packed
• 1/4 cup granulated sugar
• 1/4 cup old-fashioned rolled oats
• 1 teaspoon ground cinnamon
• 1/2 teaspoon baking powder
• 1/4 teaspoon salt
• 1/2 cup unsalted butter, softened and cut into pieces (1 stick)

For the Glaze:

• 1 1/2 cups powdered sugar
• 2 to 3 tablespoons water or milk

Instructions:

Prepare the Crumble Topping:

1. Combine all of the ingredients in a bowl except for the butter.
2. Cut the butter in using a pastry cutter or fork until pea-sized pieces remain.
3. Set the mixture aside to allow larger clumps to form.

Make the Cake:

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

Dry the blackberries well. In another small bowl, toss them in sugar and cinnamon. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar until light and fluffy.

Add the vanilla and eggs, mixing until smooth. Mix in the sour cream.

Add the dry ingredients and mix just until combined. If you overmix, the cake may bake up dense.

Spread a thin layer of the batter evenly into the bottom of the prepared baking dish. It will be very thick – this is normal!

Sprinkle the blackberry mixture over the batter.

Drop the rest of the batter by heaping tablespoons randomly over the blackberries.

Gently spread it about evenly with a stiff rubber spatula or a wooden spoon until a flat, top layer of batter forms.

Sprinkle a very thick layer of the farmhouse crumble topping evenly across the top.

Bake for about 50 minutes or until the center is set and a toothpick comes out mostly clean. If the top starts browning too quickly, loosely tent with foil near the end of baking.

Allow to cool on a wire rack for 1 to 2 hours.

For the Glaze:

Let the cake cool completely (about 90 minutes) before drizzling with the glaze, or it will melt into the topping and disappear.

To glaze, mix the powdered sugar with 2 to 3 tablespoons of water or milk until smooth. Drizzle the glaze over the cake in a zig-zag motion with a fork or spoon. Allow to harden.

Storage & Freezing:

Store at room temperature in an air-tight container, or covered in plastic wrap for up to 3 days. Freeze any leftover slices for up to 2 months.

More Recipes for Sweet Mornings:

Apple Cinnamon Crumb Muffins

Baked Oatmeal with Fresh Summer Berries

Morning Glory Muffins

Lemon Poppy Seed Muffins

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