Ingredients
4 tablespoons unsalted butter, softened
2/3 cup confectioners' sugar, sifted, plus more for rolling
1/2 teaspoon whole milk, plus more as needed
1 log (7 ounces) marzipan, such as Odense
Black and green gel-paste food coloring and gold jimmies and shamrock sprinkles, for decorating
15 Mini Chocolate Cupcakes, homemade or store-bought
15 chocolate wafer cookies, such as Nabisco
Preparation
Beat butter on medium-high speed until pale and creamy, about 2 minutes. Reduce speed to medium, then add confectioners’ sugar and milk; mix until smooth, adding more milk as needed to create a silky buttercream.
Pinch off about 1 tablespoon marzipan and knead in some black food coloring until well incorporated. Cover with plastic wrap; set aside. Knead green food coloring into remaining marzipan. Divide green marzipan into two pieces.
Working with one piece at a time (and keeping remainder covered with plastic), transfer to a surface dusted lightly with confectioners’ sugar. Roll into a very thin circle (a scant 1/8 inch). Use a 5-inch round cookie cutter to cut out circles. Transfer marzipan circles to a baking sheet dusted with confectioners’ sugar; use a pastry brush to brush away any excess sugar.
Cover with plastic while you roll out and cut remaining green marzipan. Roll out black marzipan in the same way. Using a sharp knife or pastry wheel, cut into approximately 5-by-1/2-inch strips; keep covered with plastic.
Trim tops of cupcakes with a serrated knife if they’re domed. Spread a small amount of buttercream onto surface of a wafer cookie. Flip a cupcake upside down and place in center of cookie. Spread top and sides of cupcake with a thin layer of buttercream, then drape a piece of green marzipan over top, pressing onto cupcake to adhere.
Wrap a strip of black marzipan around brim of hat, pressing at seam to secure. Create a buckle by pressing 4 jimmies into a square on black marzipan band. Repeat with remaining cupcakes, wafer cookies, buttercream, marzipan, and jimmies. Decorate with shamrock sprinkles.
