Line 2 baking sheets with aluminum foil and set aside.
Place the Almonds in a food processor and process for exactly 2 minutes.
Place the almonds in a bowl and add the sugar, egg whites, zest and food coloring. Mix together until the color is uniform and you have a very thick paste. Chill the dough for at least one hour or overnight.
Preheat oven to 350 degrees.
Once the dough is chilled roll it out between two sheets of parchment paper using 1/4 inch rolling guides. Dust the bottoms with four and transfer to the baking sheets. Bake for 8-9 minutes.
Avoid moving the cookies off the foil until they cool. The cookies will be soft right out of the oven. They will firm up as they cool. Cool completely before decorating.
To decorate with chocolate melt the chocolate and shortening together over a double boiler and dip each heart half way. Lay on a wire rack and decorate with sprinkles while the chocolate is still wet. Allow the chocolate to dry completely.
To decorate with sugar glaze stir the sugar and milk together until you have a liquid glaze. For a thinner glaze add milk by the teaspoon until you reach your desired consistency.
Dip each heart halfway in the glaze.
Lay on a wire rack and decorate with sprinkles while the glaze is still wet. Allow the glaze to dry completely before serving.