01 -
Heat your oven to 350°F. Coat all inner parts of a 16-cup angel food cake pan with cooking spray that includes flour, or grease and flour it well. Set aside.
02 -
Use a food processor to pulse the walnuts a few times. Then toss in flour, brown sugar, and cinnamon; pulse again until mixed. Add butter and blitz until it looks like small crumbs. Chill this mixture in the fridge.
03 -
In a medium bowl, combine the flour, baking soda, baking powder, salt, and cinnamon with a whisk. Leave this aside for now.
04 -
Beat softened butter and sugar together using a mixer until fluffy (takes about 3 minutes). Crack in the eggs one at a time, mixing in between. Add the mashed bananas and vanilla, blending until well combined.
05 -
Gradually add the dry mixture to your banana batter in three parts. Alternate with sour cream. Mix lightly until just blended. Scoop out 1/4 cup of the batter to use for the cream cheese layer later.
06 -
Optional step: Stir in chocolate chips or chopped walnuts. Pour the remaining batter into the prepared pan, taking out another 1 cup of batter for topping later. Leave these aside.
07 -
Back in your mixing bowl, combine the reserved 1/4 cup of batter, cream cheese, sugar, and vanilla. Beat for just one minute until smooth. Carefully spread on top of the batter in the pan, keeping it away from the edges. Add the 1 cup of reserved batter over this layer.
08 -
Gently tap the pan to shake out any air bubbles, then layer the walnut streusel on top evenly. Bake at 350°F for 55–60 minutes or until a toothpick poked into the cake (not the cream cheese part) comes out clean.
09 -
Let the cake cool in the pan on a wire rack for an hour. Carefully flip it onto a baking sheet, then flip it again onto the rack so the streusel topping faces up. Let it cool fully.
10 -
Mix together the milk, powdered sugar, and vanilla until smooth. Drizzle over the cake once it's cooled. Sprinkle mini chocolate chips on top if you'd like. Store leftovers in the fridge for up to a week.