Pre-heat oven to 300ºF.
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 the mixer down to the lowest setting possible, and slowly add the granulated sugar. Be sure to incorporate all the sugar into the egg whites.
Turn up the mixer again on high, and keep beating egg whites until peaks form. DO NOT OVERBEAT.
Once done, pour all the almond flour and icing sugar mixture into the egg whites.
Fold the dry mixture into the egg whites with a rubber spatula until the paste flows like a ribbon.
Prepare a baking sheet with a silicone baking mat with a macaron template.
Fit a pastry bag with a #12 round tip, if using, and trim the bottom as appropriate.
Pour batter into the bag.
Pipe circles onto the prepared baking sheet. You should get about 40-60 circles.
Once piped, rap the sheet on the counter to release all the air bubbles. Use a cookie scribe or toothpick to remove any smaller bubbles.
Sprinkle with crushed oreo cookie crumbs if using.
Rest for 30 minutes until the shells have formed a skin and are no longer tacky to the touch.
Bake in the oven at 300°F for 13-15 minutes.
Check for doneness by wiggling the shell. Shells are fully baked 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.