Sour Cream Coffee Cake

Source: Barefoot Contessa Parties! by Ina Garten
Serves: 8-10

Cake:
12 T unsalted butter at room temperature
1 1/2 c granulated sugar
3 extra large eggs at room temperature
1 1/2 t vanilla extract
1 1/4 c sour cream
2 1/2 c cake flour (not self-rising)
2 t baking powder
1/2 t baking soda
1/2 t kosher salt

Streusel:
3/4 c light brown sugar, packed
1/2 c all purpose flour
1 1/2 t ground cinnamon
1/4 t kosher salt
3 T cold unsalted butter, cut into pieces
3/4 c chopped walnuts (optional)

1 c fresh or frozen blueberries (optional)

Glaze (Optional):
1/2 c confectioners' sugar
2 T maple syrup

Preheat oven to 350. Grease and flour a 10 inch tube pan. Sift together flour, baking powder, baking soda, and salt. Set aside.
Cream butter and sugar until light. Add eggs one at a time and beat well. Add vanilla and sour cream. With the mixer on low, add flour mixture and stir until just combined.
For the streusel, combine brown sugar, flour, cinnamon, salt, and butter with your fingers until it forms a crumble. Mix in walnuts, if using.
Spread half of the batter in the pan and sprinkle with 3/4 c streusel and the blueberries (if using). Spread with remaining batter and sprinkle with remaining streusel. Bake for 50-60 minutes or until a tester comes out clean.
Cool on a wire rack for 30 minutes then carefully transfer cake streusel side up to a serving plate.

Glaze if desired by whisking together confectioners' sugar and maple syrup. Drizzle over cake.