Step 1

Preheat the oven to 350 degrees. Grease and flour three 8-inch cake pans.

Step 2

In the bowl of your mixer, beat the butter until smooth. Add in the granulated and brown sugar and beat on low until combined, then on medium until smooth. This should take about 1 to 1 ½ minutes.

Step 3

Add in the eggs, one at a time and mixing until just combined after each addition.

Step 4

In a separate bowl, mix together the flour, baking powder, baking soda, salt, and cinnamon. Stir to combine.

Step 5

In another bowl, mix together the sour cream, whole milk, mashed bananas, and vanilla extract. Whisk well.

Step 6

Add your dry ingredients and your liquid ingredients alternately to the egg and sugar mixture. Beginning and ending with the flour mixture. Mix until just combined. Don't over mix.

Step 7

Fold in a cup of chopped toffee. Reserve 2-3 tablespoons for the top of cake if desired.

Step 8

Spoon evenly into prepared pans.

Step 9

Bake at 350°F for approximately 30-35 minutes. Start checking at 25 minutes.

Step 10

Remove from oven and set on racks to cool for 10 minutes. Turn out the cakes onto racks after 10 minutes to cool completely. Ice with browned butter toffee buttercream.

Step 11

Melt butter in a saucepan on medium to low heat Whisk constantly. When it turns light brown remove the pan from the heat. Cool.

Step 12

Add powdered sugar to the bowl of an electric mixer. Add heavy cream, vanilla, and browned butter to the powdered sugar.

Step 13

Beat until smooth. Add more cream if frosting is too thick (or more powdered sugar if it's too thin.)

Step 14

Wait until the cake is completely cool before frosting. For a more professional cake, remove the domes from the tops of the cake layers with a cake leveler or large serrated knife. Place one layer of cake on a serving plate. Spread about 1 cup of the frosting on top in an even layer. Repeat with the next layer of cake and frosting, then top the cake with the final layer of cake (if you have 3 layers). Frost the outside of the cake. An offset spatula makes it really easy to get an even layer.

Step 15

Store in an airtight container on the countertop for 3 to 4 days. Or, in an airtight container in the refrigerator for 6 to 7 days.