For the Cake Layers
Preheat the oven to 350°F (175°C). Grease and line two 9-inch round cake pans.
In a large bowl, whisk flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Mix eggs, buttermilk, oil, vanilla, and peppermint extract in another bowl. Combine wet and dry ingredients, then add boiling water.
Pour batter into pans and bake for 30-35 minutes. Cool completely.
For the Cheesecake Layer
Preheat oven to 325°F (160°C). Prepare a springform pan with parchment paper and foil.
Beat cream cheese and sugar until smooth. Add eggs, peppermint, and vanilla extract.
Pour into the pan and bake in a water bath for 45-50 minutes. Chill for 4 hours or overnight.
For the Fudge Frosting
Beat softened butter until creamy. Gradually add powdered sugar, cocoa, and salt.
Mix in heavy cream and vanilla until frosting is smooth and fluffy.
Assemble the Cake
Trim cake layers if needed. Place one cake layer, followed by the cheesecake layer, and top with the second cake layer.
Frost the cake and decorate with garnishes. Chill before serving.