Step 1

The toffee filling needs time to cook and cool, so I recommend making it first or in advance. Remove the label from a can of sweetened condensed milk and place the can on its side in a large pot or large saucepan. Fill with water so that the water level is at least 2 inches above the can.

Step 2

Set the pot over high heat and let the water come to a simmer.

Step 3

Reduce heat and simmer for 2 hours. Check the pot every 30 minutes to make sure the water level stays above the can. Add hot water as needed to top it off.

Step 4

Carefully remove the can from the water using tongs or a large spoon. Set the can on a wire rack and let FULLY COOL to room temperature. It is super important that the can is fully cooled before opening, otherwise the can can explode due to the heat and pressure!

Step 5

Once the can is fully at room temperature, you can either open it and pour it into an airtight container and keep it in the fridge for up to 2 weeks or store the unopened can in the fridge for up to 3 months.

Step 6

Next, make the banana cake layers. Preheat the oven to 350°F/175°C and grease and line 3, 8-inch cake pans. Set aside.

Step 7

Mash 3 large bananas with either a fork or a mixer and stir together with 2 tsp of lemon juice. This prevents the bananas from browning. Set aside.

Step 8

In a large bowl, whisk 3 cups flour, 1 tsp baking powder, 1 tsp baking soda, and 1/2 tsp salt together. Set aside.

Step 9

Use a hand mixer or stand mixer fitted with a whisk attachment to beat 1 cup of butter, 1 cup of granulated sugar, and 2/3 cup of brown sugar together. Mix on a high speed for about 3 minutes. The mixture should get lighter in color as air is whipped into it. Use a spatula to scrape the sides and bottom of the bowl as needed.

Step 10

Mix in 3 large eggs and 2 tsp of vanilla extract on a medium speed.

Step 11

Mix in half of the dry ingredients on a low speed until just combined.

Step 12

Add in 1 1/2 cups of buttermilk and mix until incorporated, then mix in the remaining dry ingredients on a low speed. Be careful not to over-mix the batter once you've added in the flour. The batter will be on the thick side.

Step 13

Mix in the mashed bananas on a medium speed until just combined.

Step 14

If desired, carefully fold in 3/4 cup mini chocolate chips.

Step 15

Divide the batter evenly between the prepared pans. Bake for 28-32 minutes, or until a toothpick inserted in the center comes out (relatively) clean.

Step 16

Remove the cakes from the oven and set on a wire rack. Run an offset spatula around the edge of the pan to help release the cake layers from the pan. Let the cakes cool fully in the pan.

Step 17

As the cake layers bake and cool, make the whipped vanilla buttercream.

Step 18

In the bowl of a stand mixer, beat 2 cups of butter on a medium-high speed for 2 minutes with a whisk attachment. The butter should become lighter in color.

Step 19

Mix in 3 Tbsp heavy cream, 2 tsp vanilla, and 1/2 tsp salt on a medium speed until combined.

Step 20

Gradually mix in 6 cups of powdered sugar on a low speed. Scrape the sides and bottom of the bowl as needed.

Step 21

Once all the powdered sugar has been mixed in, add in 1/4 cup of pasteurized egg whites (sounds weird but gives the frosting an amazingly smooth, light texture). Whip the buttercream on high for about 1 minute to make it nice and fluffy. The frosting should be rather thick, like whipped topping!

Step 22

Cover flush with plastic wrap to prevent crusting and set aside.

Step 23

Stack and frost the cake layers on a 10-inch, grease-proof, cardboard cake round or flat plate.

Step 24

Spread a tablespoon of frosting in the center of the board to help keep the first cake layer in place.

Step 25

Spread a layer of vanilla frosting on top of the cake layer, then pipe a thick ring of whipped vanilla buttercream around the perimeter of the layer. Chill the cake in the freezer for about 5 minutes, until the frosting it firm to the touch. This will make it so much easier to spread the toffee on top of it!

Step 26

Use about 1/3 of the toffee filling to spread an even layer on top of the frosting. Top with fresh banana slices.

Step 27

Repeat with remaining layers. Make sure the toffee filling and bananas stay inside the frosting ring.

Step 28

Cover the cake in a thin layer of vanilla frosting. Smooth using a large offset spatula and bench scraper, then chill in the freezer (5 mins) or fridge (30 mins) until the frosting is firm to the touch. This helps lock in all the filling and makes it easier to get a perfect, 2nd coat of frosting.

Step 29

Next, add a second, thicker layer of frosting around the cake. Smooth using a bench scraper. You can see a full tutorial on how to frost a cake with smooth sides here.

Step 30

Spread a thin ring of toffee around the base of the cake, then use a large offset spatula to drag the toffee up the side of a cake at an angle.

Step 31

Top the cake with a circle of freshly slice bananas or banana chips and a drizzle of warm toffee (I heated the toffee in the microwave for about 15 seconds). Then enjoy!