Instructions

• Preheat the oven to 350°F. Grease and flour the inside of the 19.5/10-inch 16 cup capacity angel food cake pan, or spray all inside surfaces with nonstick cooking spray with flour. Set the pan aside.
• Make the Cinnamon Walnut Streusel: place 1/2 cup walnuts in a food processor and pulse 3 times. Add 1/2 cup flour, 1/2 cup packed brown sugar, and 1/2 tablespoon cinnamon and pulse a few times to combine. Scatter 4 tablespoons cold, cubed butter over the top and pulse until the mixture resembles small pebbles and the walnuts are chopped. (Or combine in a bowl and cut in the butter by hand.) Refrigerate the streusel while you make the cake batter.
• In a medium bowl whisk together 2 1/4 cups all-purpose flour, 1 1/4 teaspoons baking powder, 1 1/4 teaspoon baking soda, 1 teaspoon salt, and 1 teaspoon cinnamon. Set aside.
• In the bowl of a stand mixer or using a hand mixer, beat 1/2 cup softened butter and 1 1/2 cups sugar on medium-high speed until light and fluffy, about 3 minutes.
• Add the 2 large eggs one at a time, beating just until the yellow of each egg disappears before adding the next. Mix in 1 tablespoon vanilla extract and 1 cup mashed bananas until just combined.
• Add the flour mixture and 1 1/4 cups sour ream (not nonfat), at room temperature, in three additions: add one third of the flour mixture, then half of the sour ream; add the second third of the flour mixture, then the remaining sour ream; add the final third of the flour mixture. Beat only until just combined after each addition.
• Measure out 1/4 cup of the batter and transfer it to a small bowl for the cream cheese filling (this is the "Reserved Batter" listed in the ingredients). Set that bowl aside.
• Stir 1/2 cup semi-sweet chocolate chips (optional) and 1/2 cup walnuts, chopped (optional) into the remaining batter until just combined.
• From the remaining batter, measure out 1 cup and set it aside—this will be used to spread over the cream cheese layer. Spoon the rest of the batter (the portion remaining after removing the 1 cup) into the prepared pan and smooth it into an even layer.
• Make the Cream Cheese Filling: in a clean mixing bowl add the reserved 1/4 cup batter, 8 ounces softened cream cheese, 1/4 cup sugar, and 1 teaspoon vanilla extract. Beat on medium-high speed until smooth and creamy, about 1 minute.
• Spoon the cream cheese filling over the batter in the pan and gently smooth it, leaving about 1/4 inch between the filling and the sides of the pan (do not spread into the pan sides). Carefully spread the reserved 1 cup of batter thinly and evenly over the cream cheese filling.
• Tap the pan on the counter a few times to release air bubbles. Sprinkle the chilled Cinnamon Walnut Streusel evenly over the top of the cake.
• Bake at 350°F for 55–60 minutes, or until a toothpick inserted into the cake portion (avoiding the cream cheese layer) comes out clean. If the toothpick is not clean at 60 minutes, continue baking and check every 5–10 minutes until done.
• Remove the cake from the oven and cool on a wire rack for 1 hour. After 1 hour, gently invert the cake onto a baking sheet, remove the pan, then invert the cake again so the streusel is on top. Let the cake cool to room temperature.
• Make the Vanilla Glaze: whisk together 1 cup powdered sugar, 1 teaspoon vanilla extract, and 2 tablespoons milk in a medium bowl until smooth. When the cake is at room temperature, drizzle the glaze over the top.
• Garnish with mini chocolate chips (optional). Store the cake in the refrigerator for up to 7 days.