Coffee Cake Recipe

Prepare oven and pan

Preheat the oven to 350°F (175°C). Grease an 8- or 9-inch square baking pan (or a 9-inch round) and line with parchment if desired for easier removal.

Mix dry ingredients

In a medium bowl, whisk together 2 cups all-purpose flour, 2 tsp baking powder, 1/2 tsp baking soda, and 1/2 tsp salt until evenly combined.

Cream butter and sugar

In a large bowl or stand mixer fitted with a paddle, beat 1/2 cup softened unsalted butter and 1 cup granulated sugar on medium speed until light and fluffy, about 2–3 minutes.

Add eggs and vanilla

Add the 2 large eggs one at a time, beating well after each addition. Mix in 2 tsp vanilla extract.

Combine wet and dry

With the mixer on low, add half of the dry ingredients to the butter mixture, then add 1 cup sour cream and 1/4 cup milk, then the remaining dry ingredients. Mix just until combined; do not overmix. Batter will be thick and smooth.

Transfer to pan

Spoon about two-thirds of the batter into the prepared pan and spread into an even layer using a spatula. Reserve the remaining batter for the top layer.

Make streusel

In a bowl, combine 3/4 cup all-purpose flour, 1/2 cup packed light brown sugar, 2 tbsp granulated sugar, and 1 tsp ground cinnamon. Add the cold cubed butter (6 tbsp) and use a pastry cutter, two forks, or your fingertips to cut the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-sized pieces. Stir in 1/2 cup chopped nuts if using.

Assemble layers

Sprinkle half of the streusel evenly over the batter in the pan. Dollop the reserved batter over the streusel and gently spread to cover without pressing the streusel too far down. Sprinkle the remaining streusel evenly over the top.

Bake

Bake in the preheated 350°F (175°C) oven for 35–45 minutes, until the top is golden brown and a toothpick inserted into the cake (not the streusel) comes out with a few moist crumbs but no raw batter. If the streusel browns too quickly, tent loosely with foil for the last 10 minutes.

Cool

Remove the pan to a wire rack and let the cake cool in the pan for 15 minutes. Run a knife around the edges, then remove the cake from the pan and finish cooling on the rack to room temperature, about another 30–40 minutes. Cooling slightly makes slicing cleaner and helps glaze set.

Optional glaze

If using glaze, whisk together 1 cup powdered sugar, 1 tbsp milk (or heavy cream), and 1/4 tsp vanilla until smooth. If too thick, add a few drops more milk; if too thin, add a little more powdered sugar. Drizzle the glaze over the cooled cake with a spoon or piping bag and let set for 10–15 minutes before serving.

Serve

Slice the coffee cake into squares or wedges. Serve at room temperature with coffee or tea. Store leftovers covered at room temperature for up to 2 days or refrigerated for up to 4 days; warm slightly before serving if chilled.