01 - Preheat oven to 350°F. Grease and line the bottom of a 9-inch springform pan with parchment paper.
02 - In a large mixing bowl, combine flour, sugar, cocoa powder, baking powder, baking soda, and salt.
03 - Add buttermilk, hot water, oil, egg, and vanilla. Mix until smooth and well combined.
04 - Pour batter into prepared pan and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
05 - Let the cake cool in the pan for 10 minutes, then remove from pan and cool completely on a wire rack.
06 - Line the cleaned springform pan with plastic wrap or parchment. Place the cooled cake layer at the bottom.
07 - Spread softened mint chocolate chip ice cream evenly over the cake layer. Smooth the top with a spatula.
08 - Cover and freeze for at least 4 hours, or until firm.
09 - Beat heavy cream, powdered sugar, and vanilla until stiff peaks form.
10 - Heat heavy cream until just simmering and pour over chocolate chips. Let sit 2 minutes, then stir until smooth.
11 - Remove cake from freezer. Release from pan and transfer to a platter. Spread or pipe whipped cream on top, drizzle with ganache, and sprinkle with mini chocolate chips and mint leaves.
12 - Slice with a hot, sharp knife and serve immediately.