Coffee Cake Banana Bread with Cinnamon-Walnut Streusel

Coffee Cake Banana Bread with Streusel

This square-pan banana coffee cake has tender banana crumb, a cinnamon-walnut layer through the middle, and coarse streusel on top. One batch of streusel makes both layers, while fresh banana rounds and walnuts finish each plated square.

Measure the mashed banana rather than relying on a banana count. The moist center may need longer than the topping takes to brown, so check the cake beneath the streusel before taking it out of the oven.

Ingredients for Coffee Cake Banana Bread

Banana cake

• 1 3/4 cups all-purpose flour (210g)
• 1 teaspoon baking soda
• 1/2 teaspoon baking powder
• 1/2 teaspoon fine salt
• 1/2 cup unsalted butter, softened (115g)
• 2/3 cup granulated sugar (135g)
• 2 large eggs
• 1 teaspoon vanilla extract
• 1 cup mashed very ripe banana, from about 2 to 3 medium bananas (225g)
• 1/3 cup sour cream (80g)

Cinnamon-walnut streusel

• 3/4 cup all-purpose flour (90g)
• 1/2 cup packed light brown sugar (100g)
• 1 1/2 teaspoons ground cinnamon
• 1/2 cup chopped walnuts
• 5 tablespoons cold unsalted butter, cubed (70g)

For serving

• About 2 medium fresh bananas, sliced as needed
• 2 tablespoons chopped walnuts

Full-fat plain Greek yogurt can replace the sour cream in the same amount. If using frozen bananas, thaw them and drain off any conspicuous excess liquid before mashing and measuring 1 cup.

How to Bake Coffee Cake Banana Bread

1. Prepare the pan: Position a rack near the center of the oven and preheat to 350°F (175°C). Line a 9 x 9-inch square pan with parchment extending over two sides, and lightly grease the exposed sides.
2. Make the streusel: Combine the streusel flour, brown sugar, cinnamon, and 1/2 cup walnuts. Cut in the cold butter with a fork or pastry blender until uneven crumbs form, ranging from pea-size pieces to larger clumps. Refrigerate while making the batter.
3. Mix the batter: Whisk the cake flour, baking soda, baking powder, and salt in a bowl. In another bowl, beat the softened butter and granulated sugar together, then beat in the eggs and vanilla. Mix in the measured banana and sour cream. Fold in the dry ingredients just until no flour streaks remain; further mixing can make the cake dense.
4. Build the layers: Spread half the batter in the pan. Scatter about one-third of the streusel over it, reaching nearly to the edges. Gently spread on the remaining batter without dragging the filling through it. Scatter the rest of the streusel on top in loose clumps; do not press it flat.
5. Bake: Bake uncovered for approximately 45 to 55 minutes, beginning to check at 40 minutes. The center should feel set, and a tester inserted into a cake-crumb area near the center—not just the cinnamon filling—should come out with no wet batter. A few moist crumbs are fine. If the topping darkens before the center is done, tent the pan loosely with foil and continue baking. Rotate the pan if your oven browns noticeably unevenly.
6. Cool and serve: Cool in the pan for about 20 minutes, then lift the cake out by the parchment and cool on a rack for about 25 minutes more, until the squares hold together when cut. Cut into 9 thick squares. Just before serving, top each square with two fresh banana rounds and a few of the serving walnuts.

Why Pan Size Affects the Bake

The 9 x 9-inch pan produces the intended thick, square-cut portions. An 8 x 8-inch pan makes a deeper cake that will need a doneness-based adjustment; a loaf pan changes both the shape and baking schedule. Dark metal and glass pans can also affect edge browning, while wetter banana mash can extend the bake. Rely on the center rather than the clock or the color of the streusel alone.

For a traditional loaf instead, see this classic moist banana bread.

Serving and Storing the Squares

Serve at room temperature or briefly warm an individual square in the microwave before adding the fresh banana and walnuts. Slice the serving bananas just before plating; they are not part of the baked topping.

Store fully cooled squares without the fresh banana garnish, covered at room temperature for about 3 to 4 days. The streusel will gradually soften. The cake can also be baked a day ahead, cooled, and covered.

To freeze, tightly wrap fully cooled, ungarnished squares for up to 2 months. Thaw before serving and add the fresh garnish afterward.

Nutrition

Approximate nutrition per serving, based on 9 squares with banana and walnut garnish: 500 calories, 7g protein, 25g fat, and 64g carbohydrates. Approximate values per 100g: 350 calories, 5g protein, 17g fat, and 45g carbohydrates. Values vary with banana size, ingredients, and moisture lost during baking.