Preheat your oven to 350°F. Grease and line three 8-inch cake pans with parchment paper.

In a medium bowl, whisk together the cake flour, baking powder, baking soda, cinnamon, nutmeg, cardamom, and salt.

In a large mixing bowl, whisk together the mashed bananas, buttermilk, vegetable oil, granulated sugar, brown sugar, eggs, and vanilla until smooth and fully combined.

Add the dry ingredients into the wet ingredients and gently mix until just combined. Be careful not to overmix the batter.

In a saucepan over medium heat, combine the brown sugar, melted butter, cinnamon, nutmeg, salt, heavy cream, and vanilla bean paste. Stir continuously for 3–5 minutes until smooth and glossy. Remove from heat and allow the filling to cool slightly so it thickens.

Divide the banana cake batter evenly between the prepared cake pans. Spoon ribbons of the cinnamon caramel filling throughout each layer and lightly swirl using a butter knife. Do not over-swirl or the layers can become muddy.

Bake for 28–32 minutes or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs.

Allow the cakes to cool in the pans for 15 minutes before transferring to cooling racks to cool completely.

For the frosting, beat the softened butter and cream cheese together until light, fluffy, and smooth.

Add the powdered sugar one cup at a time, mixing on low speed between additions.

Add the cornstarch, milk, vanilla, and salt. Beat on medium-high speed for 2–3 minutes until thick, creamy, and pipeable.

Level the cake layers if needed. Place the first cake layer onto your cake stand and spread a generous layer of cream cheese frosting on top. Drizzle additional cinnamon caramel filling over the frosting.

Repeat with the remaining layers.

Frost the outside of the cake with the remaining cream cheese frosting and decorate with extra cinnamon caramel drizzle if desired.

Chill the cake for 20–30 minutes before slicing for cleaner layers.