3/4 cup slivered almonds
2 1/4 cups all-purpose flour
1/4 teaspoon salt
1 cup butter, softened
3/4 cup sugar
1 teaspoon vanilla
1/2 teaspoon freshly grated lemon zest
1/4 teaspoon almond extract
3 cups powdered sugar
1/3 cup butter, softened
1 1/2 teaspoons vanilla
1 to 2 tablespoons milk
Place almonds into food processor bowl fitted with metal blade. Cover; process until finely ground. Combine almonds, flour and salt in bowl; set aside.
Combine 1 cup butter and sugar in bowl; beat until light and fluffy. Add egg, 1 teaspoon vanilla, lemon zest and almond extract. Continue beating, scraping bowl occasionally, until well mixed. Add flour mixture; beat at low speed until well mixed.
Divide dough in half. Shape each half into ball; flatten slightly. Wrap each in plastic food wrap, refrigerate at least 2 hours or until firm.
Heat oven to 350°F. Roll out dough, one-half at a time, on lightly floured surface (keeping remaining dough refrigerated) to 1/4 inch thickness. Cut out 3 each of 6 graduated sizes of star-shaped cookie cutters (18 cookies total). Bake similar sizes of cookies together on ungreased cookie sheet 8-12 minutes or until edges are just beginning to brown. Cool 1 minute on cookie sheet; remove to cooling rack. Cool completely.
Combine powdered sugar and 1/3 cup butter in bowl; beat at low speed until well mixed. Add 1 1/2 teaspoons vanilla and enough milk for desired frosting consistency.
Frost and decorate 1 large cookie as desired. Secure decorated cookie to serving platter with 1 teaspoon frosting. Place about 1 teaspoon icing in center of cookie. Repeat frosting as desired, decorating and securing same size cookie on top, turning it slightly so points of star are offset from previous cookie. Repeat, continuing to stack cookies in graduated sizes, reserving 1 small cookie. Stand reserved small cookie up to form tree topper, securing with frosting.