Cream butter and sugar until light and fluffy, then add eggs and vanilla, mixing well. Gradually add flour until a smooth dough forms.

Shape the dough into a disc, wrap in plastic, and chill for at least one hour.

Preheat the oven to 350°F. Roll out dough to ¼-inch thickness, cut shapes with cookie cutters, and place on lined baking sheets.

Bake cookies for 8-10 minutes until edges are set and lightly golden.

Mix powdered sugar with egg whites and lemon juice until smooth. Add food coloring as desired.

Use piping bags to apply royal icing. Add layers and decorations on wet icing.

Allow the decorated cookies to dry completely for several hours or overnight.