Preheat oven to 350°F. Line a medium baking sheet with parchment paper.
To a stand mixer fitted with a paddle attachment add the butter and both sugars and cream on medium until lightly and fluffy, about 2 minutes. Scrape down the sides as needed. With the mixer on low, add in the vanilla and almond extract followed by the eggs, one at a time, scraping down the sides in between additions.
In a small bowl combine the GF flour, salt and baking powder. Add to the butter mixture and combine until you no longer see any flour.
For drop cookies: Using a medium, 1 1/2 tbsp., sized ice cream scoop, drop the cookies onto the prepared baking sheet. Do not press down.
Bake for 11-13 minutes until golden brown around the edges and puffed. The bottom will get darker than the tops. Remove and let cool for 5 minutes then transfer to cool fully on a cooling rack. Continue with remaining dough.
For the frosting combine 2 cups powdered sugar with 2 1/2 tbsp. milk. Whisk together. Frost each cooled cookie then sprinkle with desired toppings. Will keep in an airtight container for 3-4 days.
For roll-out cookies: Scrape out the dough onto a clean surface and form into a 8x8 rectangle. Wrap tightly with plastic wrap and place in the fridge for 1 hour, up to 3 days.
Remove the chilled dough and cut into 4 equal pieces. Lightly flour a clean surface and roll the dough to 1/2-inch thick. Cut out using your desired cookie cutters placing each cookie on the prepared baking sheet, leaving a 1-inch border around. If the dough has gotten too warm, place in the fridge for 15 minutes before baking. This ensures the cookies keep their shape.
Bake for 10 minutes or until golden around the edges and bottom. Remove and let cool slightly then remove to a cooling rack to cool fully. Continue with remaining dough. If it gets too warm roll into a ball, cover with plastic and place in the fridge to chill.
To make the icing add 2 egg whites to a mixer and whip until frothy and light. Slowly add in 3 cups powdered sugar, little by little until stiff peaks form. Add food coloring or scoop into a piping bag and decorate the cookies as desired. Top with sprinkles.