This chocolate chip banana crumb cake is tender and moist, making a delicious brunch baked good or dessert. Covered in a rich and buttery crumb topping, this crumb cake recipe will be a family favorite.
Two weeks ago it was all about crumb topping, so I couldn’t leave you hanging on the crumb cake itself. In traditional recipes, the cake portion isn’t exactly groundbreaking or where the emphasis lies. I mean, with a a crisp and buttery layer of crumbs on top, why would it be?
The cake in crumb cake tends to be an afterthought. But! It doesn’t have to be.
When I find myself with several overripe bananas, this banana crumb cake is first on my list when I’m feeling in the mood for a more dessert baked good (sorry, naturally sweetened banana bread).
Why This Recipe Works
- The buttermilk and mashed banana combo means that the cake portion of this crumb cake is a lot moister than plain versions, which can lean dry.
- Using mini (and not full-size) chocolate chips balances the chocolate-y flavor with the banana without overwhelming.
- It’s easy to customize the crumb layer to your liking — simply double the recipe and scatter over top if you’re a really big crumb fan.
- Bananas: Because bananas range in size, this recipe calls for one cup of mashed banana to keep things precise. This is usually around two large or 3-4 small/medium bananas. And be sure that they are overripe (ones with many dark spots) as they have more natural sugars and provide extra liquid to the recipe.
- Buttermilk: Store-bought buttermilk is great to use, but a homemade substitute works just fine here. Your favorite variety of milk (I usually use 2%) combines with either white vinegar or lemon juice to accomplish an acidic, thicker milk. See the full instructions in the recipe card notes for this kitchen tip MVP.
- Chocolate chips: Mini semisweet chocolate chips provide a present but less intense chocolate taste. There aren’t any huge chunks of chocolate to bite into that will dominate the flavor. That said, you can use regular-sized chocolate chips or chunks if that’s what you prefer.
These simple ingredients (melted butter, flour, brown sugar, and cinnamon) are all you need for crumb topping, linked in the recipe card. While one batch yields enough to cover the top surface generously, it isn’t piled super high like good old New York crumb cake. If that’s what you’re after, all you need to do is double the crumb topping!
- Start by greasing and flouring an 8-inch square baking dish. You can use butter or cooking spray for greasing, then add a tablespoon or so of flour to the pan and shake it all over so a layer of flour adheres to the bottom and sides of the pan. Shake out the excess.
- Cream together the room temperature butter and sugar together on medium speed for several minutes until light, creamy, and smooth.
- Add the remainder of the wet ingredients to the creamed butter/sugar. While my preference is to first mash the banana separately as to ensure it’s as smooth as it can be, you can just add the overripe bananas right in the bowl during this step.
- Mix well until evenly combined.
- Whisk together the flour, baking powder, baking soda, and salt in a separate bowl, then pour it into the bowl with the wet ingredients.
- Stir the dry ingredients into the wet by hand until just combined. We don’t want to overmix because when the flour hits liquid, the gluten starts activating. Overworking the batter at this step can cause the gluten to strengthen more than you’d like for a cake, leading to drier baked goods with a tougher crumb.
- Next add the chocolate chips…
- …and fold them into the batter until they’re dispersed evenly.
- Pour the batter into the prepared pan and level out the top with a spatula or spoon.
- Prepare the crumb topping and scatter it evenly over top of the crumb cake. Bake for 35-40 minutes, or until a tester comes out clean. Let it cool in the pan completely before slicing into squares, dusting with powdered sugar, and serving.
- Greasing and then flouring the pan is helpful for two reasons. For one, the batter grips the flour coating to help the cake rise while it bakes. The other is for maximum releasability. The flour acts as a buffer between the cake and the butter/spray so it doesn’t all get absorbed by the cake.
- It’s important to use buttermilk here instead of just regular milk. The acidity of buttermilk is needed to react with the baking soda so this banana crumb cake can rise fully in the oven. See recipe card notes for an easy homemade buttermilk substitute.
- The particular crumb cake you see in these photos was made using one batch of crumb topping. You can double the crumb topping recipe if you want a SUPER thick layer of crumbs on top.
Because baking powder starts reacting once it’s mixed with liquid, it can lose its rising “potency” the longer it sits before baking. For that reason I don’t recommend preparing the batter and then waiting for some time before baking.
Once this banana crumb cake has completely cooled, wrap it snugly in plastic wrap or store it in an air-tight container or bag and keep it at room temperature. It should stay for several days or longer.
Have more overripe bananas? These recipes will help you use them up in *delicious* ways.
If you’ve enjoyed this recipe, I’d love for you to leave a star rating in the recipe card and/or a comment review below!
Chocolate Chip Banana Crumb Cake
- ½ cup (8 Tablespoons) unsalted butter softened to room temperature
- ¾ cup granulated sugar
- 1 cup mashed banana
- ½ cup (4 oz) buttermilk (see note on homemade)
- 1 large egg
- 1 ½ teaspoons vanilla extract
- 1 ½ cups all-purpose flour
- 1 teaspoon baking powder
- ¾ teaspoon baking soda
- ¼ teaspoon plus ⅛ teaspoon salt
- ¾ cup mini chocolate chips
- 1 batch crumb topping (or two batches, see note)
- Confectioners' sugar for serving
- Preheat oven to 350°F. Grease and flour an 8"x8" square pan.
- Cream softened butter and granulated sugar in a large mixing bowl on medium to medium-high speed for 1-2 minutes until light and fluffy.
- Add mashed banana, buttermilk, egg, and vanilla extract and mix until evenly combined.
- In a separate mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
- Add the dry ingredients into the bowl with the wet ingredients and stir until just combined, making sure not to overmix. Some lumps in the batter are okay. Fold in chocolate chips.
- Pour out the batter into the prepared pan, smoothing the top with a spatula so it's even.
- Prepare the crumb topping according to recipe instructions (link in the ingredient list above). Evenly scatter crumb topping over top of the crumb cake.
- Bake for 35-40 minutes, or until a tester inserted in the center comes out clean. Let the cake cool in the pan completely before slicing. Dust with confectioners' sugar just prior to serving.
- Grease and flour the pan by coating the bottom and sides with butter (or non-stick spray). Sprinkle 1-2 Tablespoons of flour into the greased pan, shaking and tilting it until the flour coats all sides. Tap out any excess flour before filling the pan with batter.
- Wait until the cake has completely cooled to room temperature before slicing and dusting with powdered sugar. Otherwise the cake can crumble and the sugar will melt into the topping.
Nutritional information is provided as an estimate. As it can vary due to many factors (brands used, quantities, etc.), we cannot guarantee its accuracy.
Cake portion adapted from The Kitchn.