01 - Preheat oven to 350°F. Grease and line a 9-inch springform pan with parchment paper.
02 - In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.
03 - Add milk, oil, eggs, and vanilla extract to the dry mixture. Mix until fully incorporated. Stir in hot water until batter is smooth and thin.
04 - Pour batter into prepared pan. Bake for 22-25 minutes or until a toothpick inserted in the center comes out clean. Cool completely in the pan on a wire rack.
05 - Spread softened mint chocolate chip ice cream evenly over the cooled cake layer. Smooth the surface with an offset spatula. Freeze for at least 3 hours until firm.
06 - Heat heavy cream in a small saucepan until just simmering. Pour over chocolate chips in a heatproof bowl. Let sit for 2 minutes, then stir until completely smooth and glossy.
07 - Allow ganache to cool slightly until thickened but still pourable. Pour evenly over the frozen ice cream layer, spreading to cover. Freeze for 30 minutes until set.
08 - Garnish with mini chocolate chips and fresh mint leaves if desired. Run a warm knife around the pan edge, release the springform, and slice into portions.