Prepare the chocolate cake base first. Preheat oven to 350F. Line baking pan one, 8-inch spring form pan with parchment paper and spray sides with baking spray. In a large mixing bowl, cream together the softened butter and sugar. Then add in the eggs and vanilla extract. Mix again until creamy, then add the warmed milk.
In a separate bowl, combine all the dry ingredients: flour, cocoa powder, salt and baking powder. Mix together, then sift into the cake batter to get rid of any clumps. Using a hand whisk, mix the flour into the batter just until combined. Be careful not to over-mix the batter! Gently fold in melted chocolate at the very end. Pour the batter into the prepared pan and bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center comes out clean. Remove the cake and let it cool on a wire rack.
Irish Cream Mint Cheesecake:
While the chocolate cake is cooling, reset the oven to 325F and prepare the cheesecake filling. Place the softened cream cheese into a mixing bowl and whisk on high speed for 5 to 6 minutes, until the cream cheese is fluffy; scrap down the sides of the bowl often. Next, add the eggs, sugar and Irish cream. Mix again for a few minutes until creamy. Add the peppermint oil and a few drops of green food coloring last. Fold in the chopped chocolate mint candies.
Before pouring the cheesecake batter over the cake layer, soak the chocolate cake layer generously with the 1/2 cup Irish cream using a pastry brush; this will moisten the layer and make it more fudgy. Pour the batter over the top and level it with an offset spatula. Bake the cheesecake at 325F for 1 hour to 1 hour and 15 minutes, until the center is set. Remove the cheesecake from the oven and let it cool first on a wire rack, then place into the fridge or freezer to cool completely.
Irish Cream Whipped Cream:
When the cheesecake is cooled, prepare the final whipped cream topping. Pour the chilled heavy cream into a large mixing bowl and add the sugar. Whisk on medium-high speed for 3 to 4 minutes, until stiff peaks form. In a separate bowl, whisk the cream cheese for a few minutes until smooth, then pour in the Irish cream and add a few drops of peppermint oil. Whisk again until the mixture is smooth.
Add the cream cheese mixture to the whipped cream and whisk again on high speed for about a minute, until stiff peaks form. Transfer the cheesecake from the spring form pan onto a cake stand. Spread about half of the whipped cream frosting over the top of the cake and use a spatula to level it off. Transfer the remaining frosting into a pastry bag; I used Ateco tip #847.
Drizzle the top of the cheesecake with melted chocolate: pour the melted chocolate into a ziplock bag, cut off the tip and then drizzle. Pipe generous dollops of cream along the edge of the cake, then garnish with sprinkles and macarons. Keep cake refrigerated if not serving right away. Serve any remaining cream on the side.