Spread almonds in a single layer in an oven-proof dish (I usually use a cake pan for this). Toast in the oven for 5-7 minutes or until they just start to lightly brown. Watch them, though - if you start to smell them, they're probably already starting to burn!
In a food processor, pulse toasted almonds until finely ground. Combine in a bowl with flour and salt.
In a large bowl, cream together the butter and sugar until light and fluffy. Add egg, lemon zest and extracts and beat until combined. Beat in as much of the flour mixture as you can with the mixer, stirring in the remaining flour by hand. (If using a stand mixer, you will be able to add all of the flour mixture with the mixer.)
Divide dough in half. Wrap each half in plastic wrap and chill for 1-2 hours or until dough is easy to handle.
Preheat oven to 350 degrees.
On a lightly floured surface, roll half of the dough to 1/4 inch thick. Use cookie cutters to cut into desired shape; reroll and rechill scraps as necessary. Place cutouts 1 inch apart on an ungreased cookie sheet. Repeat with the remaining half of the dough.
Bake for 8-10 minutes or until edges are light brown and centers are set. Cool on a cookie sheet for 1 minute before transferring to a wire rack. Cool completely before decorating with royal icing.
Make the royal icing:
In a large bowl, combine powdered sugar, meringue powder and cream of tartar. Add water and vanilla; beat with an electric mixer on low speed until combined, then on high speed for 7 to 10 minutes or until icing is very stiff.
If necessary, stir in enough water, 1 teaspoon at a time, to make an icing of piping consistency. For a spreadable icing, continue adding water until icing is the consistency of thick paint. If desired, add paste food coloring.
When not using icing, keep it covered with plastic wrap or a damp paper towel to keep it from drying out.
Notes
*Meringue powder (as well as paste food coloring and other specialty decorating items) can be found in the cake decorating section of hobby stores such as Michael's or Hobby Lobby.From Better Homes and Gardens Christmas Cookies