In a medium-sized saucepan, combine sugar, flour, and salt and whisk until well combined.

While whisking, gradually pour in milk and whisk until mixture is smooth. Turn stovetop heat to medium.

Whisk constantly on medium heat until mixture is thickened to a pudding-like consistency. The whisk should leave a trail through the mixture when it is ready.

Remove from heat and pour into a heat-proof container. Cover with a piece of wax paper pressed directly against the surface. Set aside and allow to cool completely to room temperature while you prepare the cake.

Preheat oven to 350F (175C) and prepare two 8” round cake pans by lining the bottoms with parchment paper and lightly greasing and flouring the sides. Set aside.

In a large bowl, whisk together flour, sugars, cocoa powder, baking soda, and salt.

Add melted butter and oil, stir well until completely combined.

Add eggs, egg yolk, and vanilla extract and stir well until batter is uniformly combined. Scrape the sides and bottom of the bowl to be sure all ingredients are well mixed.

Gradually add buttermilk and stir well.

Add hot coffee and stir until all ingredients are well combined. Scrape the sides and bottom of the bowl again.

Evenly divide batter between prepared cake pans and bake on 350F (175C) for 33-35 minutes. A toothpick inserted in the center should come out clean or with a few moist crumbs.

Allow cakes to cool for 15 minutes before inverting onto a cooling rack to cool completely before frosting.

Once the filling base has completely cooled to room temperature, place the butter in a large mixing bowl and beat on high-speed until light and fluffy.

Reduce mixer speed to medium and gradually add base mixture one heaping spoonful at a time.

Once all filling base mixture is added, scrape the sides and bottom of the bowl and stir in vanilla extract. Gradually increase mixer speed to medium-high and whip the frosting until smooth and airy.

Place in refrigerator for about 10-20 minutes to allow it to become slightly firm before assembling.

Combine chocolate and heavy cream in a medium-sized microwave-safe bowl. Microwave on high for 35 seconds. Stir well and microwave for another 25 seconds. Whisk mixture together until completely smooth.

Use a cake leveler or sharp serrated knife to level the cake layers, if needed.

Place first layer on a cake plate. Spread all of the filling evenly over the cake layer.

Top with next cake layer. Use an icing spatula to make the sides smooth so no filling is falling out.

Place cake in the freezer for 10-15 minutes before spreading ganache frosting.

Spread cooled ganache evenly over top of cake and around sides. Use a spatula to evenly cover the whole cake.

Place in fridge to let the frosting harden for at least 15 minutes. Slice, serve, and enjoy!