Heat oven to 350 degrees. Cream softened butter and brown sugar together. Separate eggs and set aside the whites. Add the yolks from the eggs to the butter/sugar mixture and mix. Add vanilla extract, salt, and gluten-free flour and mix with a spoon until the dry ingredients are blended. Roll dough into 1-inch balls. Beat egg whites slightly. Drop cookie dough balls into egg whites, and then transfer them into ground walnuts. Roll ball until coated. Place on cookie sheet approximately 2 inches apart. Before placing in oven, place your thumb in the center of each cookie and press until flattened. Bake for 10 minutes. After removing from oven, , push your thumb into the cookie again. These cookies are fragile until they are cooled.

Mix together softened butter and vanilla at medium speed. Mix in powdered sugar, one cup at a time. Gradually add the heavy cream between the cups of powdered sugar. Once all the ingredients are blended, add drops of food coloring until the desired color is achieved. Beat on high speed 2-3 minutes until frosting is fluffy. Decorate cooled cookies with buttercream icing. Enjoy!