Preheat to 335°F. Grease & line 3 8-inch pans
Mix milk & vinegar, rest for 5 minutes
Blend bananas, whisk banana purée and wet ingredients
Stir in curdled milk
Sift dry ingredients
Fold dry into wet just until smooth
Divide among pans and bake 28-32 minutes
Melt butter in a saucepan
Stir in sugar + cinnamon, cooking until glossy and bubbling
Slowly stream in cream, whisking constantly - mixture will foam
Simmer 1-2 minutes until smooth and slightly thickened
Remove from heat; stir in salt + vanilla. Cool until pourable but not runny
Once completely chilled, add milk to achieve desired consistency, start with 1 tbsp
Beat butter + cream cheese
Add powdered sugar gradually
Mix vanilla + salt
Thin with milk to get desired consistency
Pipe a thin buttercream dam on each cake layer
Spread a very thin layer of cream cheese frosting inside the dam
Spoon filling over frosting
Repeat for the second layer. Top with third cake layer
