Sour Cream Coffee Cake

From Martha Stewart

This recipe is a classic. It comes right off the package of King Arthur Flour.

Yield Serves 12

Ingredients
    2 teaspoons ground cinnamon
    2 teaspoons pure vanilla extract
    1/2 cup coarsely chopped walnuts
    8 tablespoons (1 stick) unsalted butter, room temperature, plus more for pans
    2 cups all-purpose flour, plus more for pans
    1 teaspoon baking powder
    1 teaspoon baking soda
    1/2 teaspoon salt
    1 cup sugar, plus 1/2 cup for topping
    2 large eggs
    1 cup sour cream

Method
Preheat the oven to 350°F. Make the topping: In a small bowl combine 1/2 cup sugar, cinnamon, vanilla, and walnuts; set aside.
   
Make the cake: Butter and flour a 9-inch springform pan; set aside. In a medium bowl, whisk together flour, baking powder, baking soda, and salt; set aside.
   
In the bowl of an electric mixer fitted with the paddle attachment, beat together butter, sugar, and eggs until smooth. Add the flour mixture alternating with the sour cream, beginning and ending with the flour mixture.
   
Spread half of the batter into the prepared baking pan, and sprinkle with half of the topping. Repeat with remaining batter and topping.
   
Bake until a cake tester inserted in the center comes out clean, 25 to 30 minutes. Cool for 15 minutes, then remove sides of pan and place on a wire rack to cool completely. Serve topping side up.