Begin by lining two clean baking sheets with parchment paper cut to fit them or silicone mats. Trim off the end of a new piping bag and fit it with a clean piping coupler.
Separate the 4 egg whites from the yolks, weight them out to 120 grams, then set them aside in a clean mixing bowl to come to room temperature.
Weigh and measure out the rest of your ingredients to have them ready, then sift the almond flour and powdered sugar through a mesh sieve to remove any lumps and combine them well. You can also pulse them together in a food processor until thoroughly mixed. Add in the salt and stir well.
When the egg whites are at room temperature, begin to beat them with an electric hand or stand mixer using the beater attachment. Once they have become frothy, add in the cream of tartar and slowly pour in the granulated sugar while beating.
Continue to beat the egg whites until they are at the stiff peak stage, meaning that the meringue stays in straight peaks when you lift a beater out of it. Mix in the vanilla extract and any gel food coloring you wish.
Stir one third of the almond flour and powdered sugar mixture into the egg whites with a rubber spatula. Once it’s mixed in, add the rest of the dry ingredients and gently fold it into the egg whites. Continue doing this until the batter comes off of the spatula in thick ribbons--you should be able to draw a figure eight with it when it’s the correct consistency.
Once your batter is ready, fold down the edges of the prepared piping bag and fill with the batter. Then, fold up the edges, twist the bag shut, and place the twist in the joint of your thumb. You will have to repeat this more than once as all of the batter won’t fit in a piping bag. Holding the bag straight over the parchment paper, squeeze gently to a count of three, then stop squeezing, pull the bag away, and repeat. Leave 1-1 ½” between each of the cookies.
Preheat the oven to 300° and set the macarons aside to allow the tops to dry for about 30 minutes. Bake them for 15-16 minutes, turning the baking sheet halfway through the baking time. Once the tops look crisp and the lower edges look dry and set, remove them from the oven and cool completely.
While the macarons are cooling and baking, make your filling and put it in a clean piping bag fitted with a coupler and round or star piping tip. Pipe a layer of filling onto the bottoms of half of the cookies, then place a second cookie on top and gently press them together.