Pour 1½ cups (360ml) whole milk into a large bowl with ½ cup (120ml) Irish cream. Add sifted cocoa powder and 1 teaspoon vanilla extract. Whisk until completely smooth. Set aside.
Make the mint mascarpone:
Place ½ cup (120g) heavy cream into a medium mixing bowl. Add 2 tablespoons (25g) granulated sugar. Beat with an electric mixer until stiff peaks form. Refrigerate until needed. Rinse the beaters.
Add ¼ cup (50g) granulated sugar and 3 egg yolks to a large mixing bowl. Beat with the electric mixer for 5 minutes until pale and thick.
Add 1 drop green gel food coloring, 1 teaspoon vanilla extract, and ¾ teaspoon mint extract along with 8 ounces (226g) mascarpone. Beat with the electric mixer until everything is incorporated and the mixture is thick; be careful not to overwork the mascarpone.
Add the whipped heavy cream and beat until smooth and creamy, again being careful not to overmix.
Assemble the tiramisu:
Set out an 8x8 cake pan or casserole dish. Dip a ladyfinger into the Irish cream soaking liquid for about 2 seconds. Place it into the cake pan. Continue dunking and lining the bottom of the cake pan with the ladyfingers, nestling them close together. An 8x8 pan should fit about 14 ladyfingers in a single layer.
Pour half the mint mascarpone over the ladyfingers and smooth it into an even layer.
Sprinkle half the grated dark chocolate on top.
Continue dipping the remaining ladyfingers into the soaking liquid, then arrange them tightly on top of the mascarpone.
Finish by pouring the remaining mint mascarpone over the ladyfingers and finish with the remaining grated dark chocolate.
Chill the tiramisu:
Cover the dish and refrigerate for at least 4 hours, preferably overnight.
To serve:
Remove the tiramisu from the refrigerator and scoop it into dessert coupes. Serve with stem-on maraschino cherries on top, if desired. Enjoy!