In a medium bowl, sift the almond flour and powdered sugar together and mix. Set aside
In a large glass bowl, add egg whites and beat until foamy. Add cream of tartar and beat to mix in. Add sugar slowly while beating on low-med speed. Keep mixing until stiff peaks form. Don't over mix. Check for those peaks regularly.
Add lemon extract and food coloring. Mix until stiff peaks again. This should not take long.
Gently fold in half of the almond flour/powdered sugar mixture. Then fold in the other half. You should fold 50-60 times total. By this point it should "flow like lava". If it is too runny add just a bit more powdered sugar/almond flour. If it is too thick try whipping the batter to get some of the air out. This may or may not help.
Scrape batter into a piping bag. Using a piping bag(I don't even put a tip on) gently, but firmly, squeeze the piping bag making 1 inch rounds onto prepared baking sheet with silicone liner. Once the tray is completed drop the sheet pan onto the counter several times to bring the air bubbles to the surface.
Preheat oven to 300 degrees. Let the macaroons sit at room temperature for 20 minutes or until a "skin" has formed on them and they are slightly firm to the touch.
Bake for about 13 minutes. Macaroons should not be soft or move when done. They should not brown either. Let cool on baking sheet for 2-5 minutes before removing to a cooling rack.
When cooled, put a dollup of lemon curd in the center of one macaroon and pipe lemon buttercream frosting in a ring around that using a piping bag with a small round tip. Place a macaroon of similar size on top and press VERY gently.
Store in the fridge or freezer. When thawing from freezer, place in fridge for 24 hours before serving.