Preheat oven to 350°F.

Grease and flour (2) 9” round cake pans. Line bottom of pans with parchment paper. Set pans aside.

Using a double boiler, add chocolate chips. Heat, stirring occasionally, until chocolate chips are fully melted. (Note: If you don’t have a double boiler, just set a heatproof bowl over a saucepan of gently simmering water.)

Add egg yolks and buttermilk; carefully stir until well combined.

Cook, stirring occasionally, for 3-4 minutes, or until mixture is smooth.

Remove mixture from heat and let cool.

Meanwhile, using a countertop mixer, cream together the butter and brown sugar until light and fluffy (~2-3 minutes on medium speed).

Using a separate bowl, sift together the flour, baking soda and salt.

Add half of the flour mixture to the bowl of the countertop mixer; mix on low speed until well combined.

Add coffee and vanilla extract; mix on low speed until well combined.

Finally, add the cooled chocolate mixture; mix on low speed until well combined.

Using a small saucepan, add all of the ingredients (butter, sugar and rum).

Place over medium-low heat and cook, stirring occasionally, until sugar has completely dissolved and mixture is smooth.

Using a small saucepan, add chocolate chips and evaporated milk.

Place over low heat and cook, stirring occasionally, until chocolate chips have completely melted and mixture is smooth. (Note: Do not let this mixture boil.)

Add egg yolk and stir until well combined.

Remove pan from heat and let glaze cool to room temperature.

Using a hand mixer or a countertop mixer fitted with the whisk attachment, add the whipping cream, confectioner’s sugar and vanilla extract; whip until stiff peaks form.

Remove one layer of cake from pan and place on a large plate. Spread ~½ of the chocolate glaze on top of the cake.

Repeat process with the second layer of cake and remaining chocolate glaze.

Spread whipped cream on top and around sides of the cake.

Sprinkle top of cake with chocolate shavings.