Whisk the egg yolks and 2 tablespoons coffee liqueur in a medium bowl. Whisk the milk, granulated sugar, cocoa powder, cornstarch and salt in a medium saucepan until smooth. Bring to a simmer over medium heat, whisking occasionally, until slightly thickened, about 8 minutes. Remove from the heat and whisk about 1/2 cup of the hot milk mixture into the beaten eggs, then whisk the egg mixture into the remaining milk in the pan. Cook over medium heat, whisking, until thickened, about 5 minutes (the whisk should leave a thick trail when dragged). Remove from the heat. Add the chopped chocolate and whisk until smooth, then whisk in the butter and 1 teaspoon vanilla.
Divide the pudding among 4 ramekins or small bowls. Place a piece of plastic wrap directly on the surface of each and refrigerate until set, at least 4 hours or overnight.
Whisk the heavy cream with the confectioners' sugar in a medium bowl until soft peaks form. Add the remaining 1 tablespoon coffee liqueur and 1/2 teaspoon vanilla and whisk until combined. Top the pudding with the whipped cream and chocolate-covered espresso beans.