This Coffee Cake is buttery, moist, super fluffy, and topped with an irresistible streusel crumb topping. It’s absolutely delicious any time of the day!
Preheat the oven to 350°F. Start by making the crumb mixture. In a food processor blend together the all-purpose flour, brown sugar, and cinnamon.* Then cut the cold butter into cubes and add it to the processor. Pulse the butter with the rest of the ingredients for just a few seconds until the mixture is crumbly. No need to over-pulse. You'll want some large and small crumbles. Set the crumb mixture to the side.
Now, for the cake batter, whisk together the dry ingredients (all-purpose flour, baking powder, baking soda, and salt) in a large mixing bowl.
In a separate large bowl blend the softened butter and granulated sugar together with a hand mixer until well combined. Add the eggs and vanilla to the bowl and blend together until combined. Now add the sour cream to the bowl and briefly blend with the rest of the ingredients until combined.
Add the dry ingredients to the same bowl as the wet ingredients. Blend on low speed until just combined. Do not over-mix at this point. The batter will be thick.
Line an 8x8 baking dish with parchment paper. Add half of the cake batter to the baking dish and spread it out evenly.
Next, make the cinnamon sugar mixture. In a small bowl, add the granulated sugar and ground cinnamon and mix them together.
Sprinkle all of the cinnamon sugar evenly over the first layer of cake batter.
Now add the rest of the cake batter on top of the cinnamon sugar layer. I like to do this by first adding large dollops of the batter on top. Then, using a rubber spatula, carefully spread the batter evenly around the baking dish, trying not to disturb the cinnamon sugar layer too much. Make sure the batter is spread all the way to the edges of the pan.
Add the prepared crumb mixture evenly on top of the cake. Bake the cake in the preheated oven for 45-50 minutes or until a toothpick inserted comes out clean.
Remove the cake from the oven and allow it to cool for about 15 minutes before lifting the parchment paper out of the baking dish. Cut into your desired amount of servings (I cut mine into 9 large slices). Enjoy!