• Chocolate Cake Layers
• Begin by preheating the oven to 350 F / 175 C.
• Line four 7-inch or three, 8-inch pans  with parchment rounds and spray with non-stick baking spray.
• Add 1 cup of unsalted butter into the bowl of a stand mixer or a large bowl and beat on a medium speed until smooth and creamy. Add 2 1/2 cups sugar and cream together on a high speed for 1-2 minutes with a whisk attachment or hand mixer. Scrape the sides of the bowl as needed. The mixture should become light in color.
• Mix in 4 large eggs on a medium speed, two at a time.
• In a separate bowl combine 1 cup of hot water, 1 cup of buttermilk, and 1 cup of cocoa powder. Whisk until the mixture is smooth and no clumps remain.
• Sift 3 cups of flour, 1 1/2 tsp baking powder, 1 tsp baking soda, and 1 tsp salt into a large bowl.
• Next, add 1/2 the dry ingredients into the butter/egg mixture. Scrape the sides of the bowl with a spatula to ensure the flour gets fully incorporated.
• Pour in the buttermilk/cocoa mixture and gently pulse the mixture to incorporate the liquid. If you don't, you'll end up splattering the cocoa mixture all over your kitchen!
• Add in the last half of the dry ingredients and mix on low until fully incorporated.
• Divide the batter evenly between the prepared pans. I like to use a kitchen scale to make sure each pan has the same amount of batter.
• Bake for 29-32 minutes or until a toothpick comes out with a few moist crumbs.
• Let the layers cool in the pans for about 10 minutes, then run an offset spatula around the edge of the pans to help separate the layers from the pans.
• Place the pans in the freezer for about 45 minutes, to accelerate the cooling process. Once the layers are fully cooled, carefully flip the pans and remove the layers from the pans.
• Use a serrated knife to level the top of each cake layers. Stack the cake layers on top of each other and trim in a slightly tapered shape to look like a Rolo candy (see photos above).
• Unstack the cake layers and cut a 2 1/2-inch circle from the center of the 2 middle cake layers with either a circle cutter or small knife. This will create a cavity in the middle of the cake for the caramel filling. Set the cake layers aside, or wrap them and freeze them at this point if you're making them in advance.

Caramel Filling

• Make the caramel filling while the cake layers bake and cool. This can be made up to a month in advance.
• Place a medium saucepan over medium to medium-high heat.
• Once the pan has warmed up, pour in 1 cup sugar gradually, adding 1/4 cup at a time. Wait until the sugar is mostly dissolved, then add in the next bit of sugar.
• As the sugar melts it will gradually deepen in color.
• Stir occasionally until the sugar is fully dissolved and has become an amber color, then turn off the heat.
• Gradually mix in 6 Tbsp of butter (2 Tbsp at a time), then stir in 1/4 cup of heavy cream and 1/4 tsp salt. The mixture will be thin but will thicken as it cools.
• Pour into a separate container, then place in the fridge to cool to room temperature.

Chocolate Buttercream Frosting

• Then make the chocolate buttercream frosting. Beat the butter on a medium speed for 30 seconds with a paddle attachment until smooth. 
• Add in the sifted cocoa powder, vanilla extract, and salt. Mix on low until the ingredients are fully incorporated.
• Slowly mix in the powdered sugar. Halfway through, add in the heavy cream to make the frosting easier to mix.
• Mix in the cooled, melted milk chocolate on a low speed until the ingredients are fully incorporated and the desired consistency is reached. Cover with plastic wrap to prevent crusting and set aside.

Assembling This Rolo Cake

• Stack and frost the cake layers on a greaseproof cake board or flat plate, using a dab of chocolate buttercream to help stick the first cake layer to the board.
• As you assemble the cake, spread an even layer of chocolate buttercream on each cake layer and stack the cake layers from largest to smallest. The layers with cut out sections should be the 2nd and 3rd cake layers.
• Once you've stacked and frosted the first three cake layers, fill the opening the all of the caramel filling.
• Top with the last cake layer and smooth a thin coat of buttercream around the cake with a large offset spatula and bench scraper. Freeze the cake for about 10 minutes in the freezer or 30 minutes in the fridge. This will help the buttercream between the cake layers firm up and make the cake easier to frost.
• Carefully cover the cake with a second, thick layer of chocolate buttercream and smooth using a bench scraper. Make some rings on top of the cake with the large offset spatula to look like the top of a Rolo, then enjoy!