Preheat oven to 350°F (375°F for high altitude). Grease and line three 8-inch pans with parchment.

Mix milk + vinegar, let rest 5 minutes.

Blend bananas smooth. Whisk banana purée, yogurt, oil, sugars, and vanilla until glossy. Stir in curdled milk.

Whisk flour, cornstarch, baking powder, baking soda, salt, cinnamon, nutmeg, and cardamom.

Fold dry into wet just until smooth. Batter should be thick but pourable. Don’t over-mix.

Divide evenly among pans (about 575 g each). Bake 24 minutes, until tops spring back and tester comes out clean.

Rest 15 minutes, then wrap warm layers and chill/freeze briefly to lock in moisture.

Melt butter in a saucepan.

Stir in sugar + cinnamon, cooking until glossy and bubbling.

Slowly stream in cream, whisking constantly.

Simmer 1-2 minutes until smooth and slightly thickened.

Remove from heat; stir in salt + vanilla. Cool until pourable but not runny.

Once lava is completely chilled, very slowly add milk to achieve desired consistency - start with 1 tbsp.

Beat butter + cream cheese until smooth. Add powdered sugar gradually. Mix in vanilla + salt. Thin with milk if needed. Whip until fluffy but pipeable.

Pipe a thin buttercream dam on each cake layer.

Spread a very thin layer of cream cheese frosting inside the dam.

Spoon/swirl ⅓ of the creamy goo over frosting.

Repeat for the second layer. Top with third cake layer.

Chill briefly to set.

Frost the outside with cream cheese frosting.

Drizzle warm goo on top or create a swirl finish.