Follow these detailed steps carefully for a flawless Creamy Banana Foster Cake. The process is broken down into making the cake layers, preparing the filling, and finally, assembling your masterpiece.

Step 1: Preparing the Banana Cake Layers

1. Preheat and Prep: Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans. For extra security against sticking, line the bottom of each pan with a circle of parchment paper, then grease and flour the parchment as well.
2. Combine Dry Ingredients: In a medium bowl, whisk together the all-purpose flour, baking soda, baking powder, ground cinnamon, and salt. Whisking aerates the flour and ensures the leavening agents are evenly distributed. Set this bowl aside.
3. Cream Butter and Sugars: In the large bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the softened unsalted butter on medium-high speed until it’s smooth and creamy, about 1 minute. Add the granulated sugar and light brown sugar. Continue to beat on medium-high speed for 3-4 minutes, scraping down the sides and bottom of the bowl as needed. The mixture should become light in color and fluffy in texture. This step is critical as it incorporates air, which is the foundation for a light cake.
4. Add Eggs and Vanilla: Add the room temperature eggs one at a time, beating well after each addition until fully incorporated. Once all eggs are mixed in, beat in the pure vanilla extract.
5. Incorporate Wet and Dry Ingredients: Reduce the mixer speed to low. Add the dry ingredient mixture in three alternating additions with the buttermilk, beginning and ending with the dry ingredients. (So: 1/3 dry, 1/2 buttermilk, 1/3 dry, 1/2 buttermilk, final 1/3 dry). Mix only until the streaks of flour just disappear. Do not overmix, as this can develop the gluten in the flour and result in a tough, dense cake.
6. Fold in Bananas: Gently fold the mashed ripe bananas into the batter using a rubber spatula.
7. Bake the Cakes: Divide the batter evenly among the three prepared cake pans. Use an offset spatula to smooth the tops. Bake for 28-32 minutes, or until a wooden toothpick inserted into the center of the cakes comes out clean or with a few moist crumbs attached.
8. Cool Completely: Let the cakes cool in the pans on a wire rack for 15 minutes. Then, carefully run a knife around the edges of the pans and invert the cakes onto the wire rack to cool completely. Complete cooling is non-negotiable; attempting to frost a warm cake will result in a melted, soupy mess.

Step 2: Crafting the Banana Foster Filling

1. Melt Butter and Sugar: In a large, wide skillet or sauté pan, melt the ½ cup of unsalted butter over medium heat. Once melted, stir in the dark brown sugar and ground cinnamon. Stir constantly until the sugar is dissolved and the mixture begins to bubble, forming a rich caramel sauce base.
2. Add Bananas: Add the sliced, firm bananas to the skillet in a single layer. Cook for about 1-2 minutes per side, until they are softened and coated in the caramel sauce. Be gentle when flipping them to keep the slices intact.
3. The Flambé (Use Caution!): Carefully pour the dark rum (and banana liqueur, if using) into the pan. If you have a gas stove, you can carefully tilt the pan towards the flame to ignite the alcohol. If you have an electric stove, use a long-handled lighter to carefully ignite the surface. Let the flames burn out on their own, which will cook off the harsh alcohol taste while leaving the deep, complex rum flavor. Safety Note: Always stand back and keep a pan lid nearby to extinguish the flames if necessary. If you are not comfortable with flambéing, simply let the sauce simmer for 2-3 minutes until it has thickened slightly and the alcohol has had a chance to cook down.
4. Cool the Filling: Remove the pan from the heat and transfer the filling to a heatproof bowl. Let it cool completely to room temperature. If the filling is even slightly warm, it will melt the frosting during assembly.

Step 3: Whipping the Cream Cheese Frosting

1. Beat Cream Cheese and Butter: In the large bowl of a stand mixer with the paddle attachment, or with a hand mixer, beat the softened cream cheese and softened butter together on medium-high speed until completely smooth, creamy, and free of lumps, about 2-3 minutes.
2. Add Sugar and Flavorings: Reduce the mixer speed to low. Gradually add the sifted powdered sugar, one cup at a time, until it’s all incorporated. Add the vanilla extract and a pinch of salt.
3. Whip to Perfection: Increase the mixer speed to medium-high and beat for 2-3 minutes until the frosting is light, fluffy, and smooth. If the frosting is too thick, add heavy cream or milk one tablespoon at a time until you reach your desired spreading consistency. If it’s too thin, add more powdered sugar, a quarter cup at a time.

Step 4: Assembling Your Masterpiece

1. Level the Cakes: If your cake layers have domed tops, use a large serrated knife to carefully level them. This creates a stable, flat surface for stacking.
2. Create a Frosting Dam: Place one cake layer on your serving plate or cake stand. Transfer about 1 ½ cups of frosting to a piping bag fitted with a round tip (or a zip-top bag with the corner snipped off). Pipe a thick ring of frosting around the top edge of the cake layer. This “dam” will hold the banana foster filling in place and prevent it from oozing out the sides.
3. Add the Filling: Spoon half of the completely cooled Banana Foster filling into the center of the frosting dam. Gently spread it into an even layer.
4. Stack and Repeat: Carefully place the second cake layer on top. Repeat the process: pipe another frosting dam and spread the remaining half of the filling inside it.
5. Final Layer and Crumb Coat: Place the third and final cake layer on top. Apply a very thin layer of frosting over the entire cake—top and sides. This is called a “crumb coat” and it traps any loose crumbs. Place the cake in the refrigerator for 20-30 minutes to set the crumb coat.
6. Frost the Cake: Once the crumb coat is firm, apply the remaining frosting to the top and sides of the cake, using an offset spatula or bench scraper to create a smooth or textured finish as you desire. You can create decorative swirls on top or keep it sleek and modern.
7. Chill and Serve: For the best flavor and cleanest slices, chill the finished cake in the refrigerator for at least 30-60 minutes before slicing and serving. This allows the frosting and filling to set firmly.