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 just combined, then stir in hot water until batter is smooth (batter will be 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.
05 - Spread softened mint chocolate chip ice cream evenly over the cooled cake. Smooth the surface with an offset spatula and freeze for at least 3 hours until firm.
06 - Heat heavy cream in a saucepan until just simmering. Pour over chocolate chips in a heat-proof bowl, let sit for 2 minutes, then stir until completely smooth.
07 - Let ganache cool slightly until thickened but still pourable, then pour over the frozen ice cream layer, spreading evenly. Return to freezer for 30 minutes.
08 - Run a warm knife around the edge of the pan, release the springform, and slice. Garnish with mini chocolate chips and fresh mint leaves if desired.