Line three baking sheets with parchment paper; set aside.

Place the egg whites in your mixer's bowl and mix until frothy; gradually pour in the superfine sugar, and continue to beat until the mixture is glossy and stiff peaks form.

At this point, you may want to add in a few drops of food coloring and mix just until combined. Set aside.

Sift together the almond flour and powdered sugar into a large mixing bowl.

With a large spoon, mix well to incorporate the almond flour and sugar.

Using a rubber spatula, gently fold in 1/4 of the meringue into the almond mixture. Continue folding the rest of the meringue until completely incorporated.

Fit a piping bag with a 3/8-inch round tip and fill it with the macaron mixture.

Pipe the batter into small rounds onto the prepared baking sheets.

Allow to dry at room temperature for 1 hour.

Preheat oven to 315°F (157°C).

Bake the macarons for 12 to 15 minutes; cookies are done when they no longer jiggle when you touch them on top. Rotate the baking sheet after 6 minutes for even baking.

Remove macarons from oven and transfer to a cooling rack; do not remove from baking sheets.

Let completely cool.

In a small mixing bowl, beat egg whites and salt.

Gradually add sugar, and continue to beat until soft peaks form.

Microwave corn syrup on high for 1.5 to 2 minutes, or until boiling.

Slowly pour a stream of the corn syrup over the egg whites, beating until mixture is stiff and glossy.

Add vanilla and beat until thoroughly combined.

After the macarons have completely cooled, turn half of the shells on their backs and pipe about 0.5 teaspoon of the filling onto each, then top with another shell.

Once all of your macarons are assembled, put them in an airtight container in the refrigerator and let them rest for 24 hours.