- 6 Tbsp unsalted butter
- 3/4 cup flour
- 1/2 cup sugar
- 1/2 cup light brown sugar
- 1 tsp cinnamon
- 1/4 tsp salt
- 1 Tbsp ice water
- 1 1/2 cups flour
- 1 tsp baking powder
- 1/2 tsp baking soda
- 1/4 tsp salt
- 6 Tbsp unsalted butter, at room temperature
- 3/4 cup sugar
- 1 1/2 tsp vanilla extract
- 1 large egg plus 1 egg yolk, at room temperature
- 2/3 cup plain fat-free Greek yogurt, at room temperature
- 1/3 cup low-fat buttermilk, at room temperature
- Preheat oven to 350°F and spray an 8-inch square baking pan with nonstick spray; dust lightly with flour.
- For the streusel, cook butter in a heavy saucepan over medium heat, stirring constantly until it foams, turns clear, and then turns a medium brown, about 5 minutes. Pour browned butter into a glass measuring cup and let cool for 5 minutes.
- Whisk together flour, sugar, brown sugar, cinnamon, and salt in a medium bowl. Add cooled butter and mix in with a fork until completely incorporated. Add ice water and mix in until streusel is crumbly. Chill until ready to use.
- For the cake, whisk together flour, baking powder, baking soda, and salt in a medium bowl. Beat butter, sugar, and vanilla in a large mixer bowl at medium speed until light and fluffy. Add egg and yolk one at a time and beat well. Combine yogurt and buttermilk in a small bowl. Reduce speed to low and add flour mixture in three additions, alternating with yogurt mixture (begin and end with flour mixture).
- Spoon half the batter into prepared pan, and smooth with an offset spatula. Tap sharply to reduce air bubbles. Sprinkle 1/2 cup chilled streusel over the cake batter. Spoon remaining cake batter over the streusel, gently smoothing with offset spatula into an even layer. Tap pan sharply, and sprinkle with remaining streusel.
- Bake for 40 to 44 minutes, until coffee cake is golden, springs back to the touch, and a toothpick inserted in the center comes out clean. Cool in pan on a wire rack for at least 1 hour before serving.
Keywords: Brown Butter, Cinnamon, Streusel