1 1/2 sticks unsalted butter, room temperature
1 1/4 cups granulated sugar
4 large eggs, room temperature
2 teaspoons pure vanilla extract
1 1/4 cups sour cream
2 1/2 cups cake flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon kosher salt
1/4 cup brown sugar
1/2 cup all-purpose flour
1 1/2 teaspoons ground cinnamon
1/2 teaspoon salt
3 tablespoons cold unsalted butter, cut into pieces
3/4 cup chopped walnuts
1. Select the BAKE function and preheat MAXX to 350°F for 5 minutes.
2. Grease and flour a 10-inch tube/Bundt pan.
3. Beat butter and sugar in the bowl of an electric mixer fitted with the paddle attachment for 3 minutes, until light and fluffy.
4. Add eggs, one at a time, incorporating well after each addition. Add vanilla and sour cream.
5. In a separate bowl, sift together flour, baking powder, baking soda and salt.
With the mixer on low speed, add dry ingredients to wet and mix until just combined. Use a spatula to stir the batter until completely mixed but not overworked.
6. For the streusel, place brown sugar, flour, cinnamon, salt, and butter in a bowl and crumble the mixture together with your fingers until the texture resembles small peas. Stir in the walnuts.
7. Spoon half of the batter into the pan, spreading it out evenly. Sprinkle 3/4 cup of the streusel on top of the batter. Spoon the rest of the batter into the pan and spread it out. Scatter the remaining streusel on top.
8. Bake for 30 to 35 minutes, or until a cake tester or toothpick inserted into the middle of the cake comes out clean.
9. Allow the cake to cool on a wire rack for at least 30 minutes. Carefully transfer the cake to a serving plate. Serve with coffee or tea.