Instructions

For the Banana Cake Layers:

1. Preheat oven to 350℉ (177℃). Prepare four 8x2-inch round cake pans with parchment rounds, and grease the sides. Set aside.
2. In a large bowl, sift the flour, baking powder, baking soda, salt and cinnamon and whisk to combine. Set aside.
3. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium-high speed until light and fluffy, about 2-3 minutes. Use a rubber spatula to scrape down the sides and bottom of the bowl.
4. Add oil, sour cream and vanilla and mix until combined.
5. Lower the speed to medium-low and add the eggs one at a time. Mix each egg until just combined before adding another. Make sure to occasionally stop and scrape down the bowl.
6. Gradually add the dry ingredients and slowly mix until just combined. Add banana purée or mashed bananas and mix until well combined. Do NOT Overmix. Batter should be thick.
7. Divide batter equally between four cake pans (or however many you have. Just wash and re-use), about 2 cups per pan. Spread into an even layer using an offset spatula. Bake 2 layers at a time for 25-30 minutes or until a toothpick inserted into the centre comes out clean and cake springs back when lightly touched.
8. Remove cakes from oven and allow to cool in pans for 10 minutes, then turn onto cooling racks to cool completely before frosting.

For the Caramel Buttercream:

1. In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a hand mixer, beat the butter and half of the powdered sugar on medium speed until pale and fluffy (starting on low speed to avoid a sugar shower), about 5-6 minutes. Scrape down the sides and bottom of the bowl.
2. Turn the mixer to low and gradually add the remaining sugar one cup at a time. Once incorporated, add 1 cup of completely cooled caramel sauce and beat until combined.
3. Once the caramel is combined, increase the mixer speed to medium-high and whip until light and fluffy, about 5-7 minutes. If the buttercream is too thick, add heavy cream or milk 1 tablespoon at a time and continue to whip until you reach the desired consistency.

Assembly of the Banana Caramel Layer Cake:

1. Once cakes are completely cooled, place one layer on a turntable. Using an offset spatula, spread about 1 cup of the caramel buttercream on top of the first layer. Drizzle some extra caramel sauce on top, if desired. Repeat with all the remaining cake layers, placing the final layer upside down.
2. Frost the entire cake in a thin layer of buttercream. Chill the cake in the refrigerator for 30 minutes.
3. Meanwhile, transfer about 1 and 1/2 cups of buttercream to a piping bag fitted with a large star tip. Set aside. If your remaining caramel sauce is too thick, heat in the microwave in 15 second intervals until it becomes pourable.
4. Remove cake from refrigerator and frost the entire cake with the remaining frosting.
5. You can decorate 1 of 2 ways: Method 1) Pipe a swirl border around the top of the cake, leaving about 1/2 an inch in between each swirl. Pour caramel sauce into the centre of the cake and allow it to drip down the sides. Method 2) Pour some caramel sauce into a small squeeze bottle, or into ziploc bag and snip off a small corner. Hold at a 90° angle slightly above the top edge of the cake and squeeze out the caramel while turning the cake, allowing the sauce to drip down the sides. Pipe the swirl border on top of the cake, leaving no space in between. Pour remaining caramel sauce into the centre of the cake.
6. Decorate with sliced bananas. Slice and serve!