Preheat the oven to 350°F. Place two of the silicone 8-cup egg molds on a baking sheet.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar until light and fluffy, about 2 minutes.
Add the eggs, one at a time, beating between each addition, then beat in the vanilla extract.
Add the flour, baking powder and 1/2 teaspoon kosher salt and beat just until combined.
Scoop about 2-tablespoon portions of the dough and roll into a ball before pressing it into the mold.
Bake the cookies until they are pale golden and set, 18 to 22 minutes. Remove the cookies from the oven and immediately use the bottom of a small spoon (or 1/2 teaspoon-sized measuring spoon) to make indentations toward the larger side of the egg.
Let the cookies cool completely in the molds before removing them onto a serving plate.
Add the frosting to a small bowl then stir in the yellow food coloring. Transfer the frosting into a piping bag or sealable plastic bag fitted with a star-shaped piping tip (optional).
Pipe the frosting into the indentations then top with orange sanding sugar and serve.