Preheat your oven to 325°F (160°C). In a large mixing bowl, sift together the all-purpose flour, corn starch, baking powder, and optional lemon zest. Set aside.

In a separate bowl, beat together the unsalted butter, shortening, and sugar using an electric mixer on medium speed until fluffy and pale.

Add egg, vanilla extract, and almond essence to the creamed mixture, mixing on low speed until smooth.

Gradually add the sifted dry ingredients, mixing on low until just combined. The dough should be slightly sticky.

If dough is too soft, chill in the refrigerator for 15-20 minutes.

Roll out the dough to 1/4-inch thickness and use a bunny-shaped cookie cutter to cut out cookies.

Bake in the preheated oven for 9-10 minutes, then cool on racks.

To make the frosting, beat softened butter until creamy, then gradually add sifted powdered sugar and adjust with milk.

Once cookies are cooled, decorate with buttercream and sprinkle sugar sprinkles and black sugar pearls.