Pre-heat oven to 300°F.
Separate the eggs from the egg whites (if using fresh eggs). Measure out 100 g (about 3 large eggs).
In a separate bowl, sift the icing sugar and almond flour together
Repeat the sifting process to ensure there are no clumps. If there are any clumps, discard them.
In a stand mixer fitted with the whisk attachment, add the egg whites and a pinch cream of tartar. Beat on high until foamy.
Once the egg whites are foamy, turn mixer down to the lowest setting possible, and slowly add in the granulated sugar. Be sure to incorporate all the sugar into the egg whites.
Add in 1 drop of Americolor teal gel food colouring.
Turn up the mixer again on high, and keep beating egg whites until peaks form. DO NOT OVER BEAT.
Once done, pour all the almond flour and icing sugar mixture into the egg whites.
With a rubber spatula, fold the dry mixture into the egg whites, until the paste flows like a ribbon.
Fit a pasty bag with a #12 round tip, if using, and trim the bottom as appropriate.
Pour batter into bag.
Pipe circles onto the prepared baking sheet. You should get about 50-60 circles in total depending on the size of your macarons.
Once piped, rap the sheet on the counter to release all the air bubbles.
Rest for 30 minutes, until the shells have formed a skin, and are no longer tacky to the touch.
Bake in oven, at 300°F for 12 minutes.
Check for doneness, by wiggling the a shell. Shells are done when they don't move from the feet. If it wiggles from the feet, then bake for another minute, and check again.
Cool the shells in the tray.