Banana Fluffernutter Lava Cake

Ingredients

Instructions

1. Prepare the pans and oven. Preheat the oven to 350°F. Grease three 8-inch cake pans and line the bottoms with parchment paper.
2. Mix the dry ingredients. In a medium bowl, whisk the cake flour, cornstarch, baking powder, baking soda, and salt until fully combined.
3. Mix the wet ingredients. In a large bowl, whisk the brown sugar, granulated sugar, oil, yogurt, vanilla bean paste, very ripe mashed bananas, room-temperature milk, and apple cider vinegar until completely smooth and emulsified.
4. Finish the batter. Add the dry ingredients to the wet ingredients and whisk gently just until combined and no dry streaks remain. Do not overmix.
5. Divide and bake. Divide the batter evenly among the prepared pans. Bake for 22–25 minutes, until the centers spring back lightly and a tester comes out clean or with a few moist crumbs.
6. Cool the layers. Let the cakes cool in their pans for 10 minutes, then turn them out onto wire racks and cool completely before assembly.
7. Make the marshmallow lava. Whisk the marshmallow fluff, salt, and vanilla bean paste until smooth.
8. Slowly stream the warm cream into the fluff while whisking continuously, until the filling is glossy and fluid. Whisk in the melted butter until completely incorporated.
9. Cool the lava. Let the filling stand for 10–15 minutes, then continue cooling it completely to room temperature. It should be slightly thickened but still pourable before it touches the buttercream.
10. Make the peanut butter buttercream. Beat the slightly cool butter on medium speed for 3 minutes, until pale and smooth. Add the peanut butter and mix until fully emulsified and fluffy.
11. Add the powdered sugar, salt, and vanilla bean paste gradually on low speed. Increase to high and beat for about 7 minutes, scraping the bowl as needed, until very light.
12. With the mixer on low, slowly stream in the room-temperature cream. Stop as soon as the buttercream is silky, fluffy, and sturdy enough to pipe a tall dam; you may not need the full amount.
13. Prepare the fresh bananas. Slice the firm-ripe bananas immediately before assembly so they stay fresh and hold their shape.
14. Build the first layer. Place one cooled cake layer on a cake board. Spread a very thin layer of peanut butter buttercream over the top, then pipe a tall, unbroken buttercream dam around the edge.
15. Add the first filling. Pour in enough room-temperature marshmallow lava to stay below halfway up the buttercream dam. Arrange fresh banana slices over the lava in a single layer without heavily overlapping them.
16. Repeat the filling. Add the second cake layer and repeat the thin buttercream base, tall dam, marshmallow lava, and fresh banana slices.
17. Finish the cake. Add the final cake layer upside down for a flat top. Apply a thin crumb coat and chill for 20–25 minutes, until stable.
18. Apply the final coat of peanut butter buttercream. Drizzle with gently warmed peanut butter and reserved marshmallow lava, if desired.
19. Chill and serve. Refrigerate the finished cake until set. For the best texture, let individual slices sit at room temperature for 15–20 minutes before eating.