Measure all ingredients out by weight. Baking is a science, and accuracy is important here! Make sure you get your measurements as close as possible.

Mix together your almond flour, powdered sugar, and cocoa powder, and sift into a bowl. If there are any large bits of almond flour left, you'll want to toss them. Your mixture should be very fine, small granules.

In the bowl of a stand mixer fitted with a whisk attachment, whip your egg whites at medium-high speed until they form a soft peak.

Combine the sugar and water in a small pan and heat to 240°F.

Once your egg whites are at a soft peak, and your sugar mixture is at 240°F, slowly pour the sugar mixture into the egg whites with the mixer running on slow speed. You will want to pour it in a small, slow, and steady stream.

Let the mixer run on medium until the mixture has cooled and the egg whites form a stiff peak.

Fold in the almond flour mixture into the egg white mixture. Be gentle, you don't want to knock too much air out of the egg whites!

Transfer the mixture into a piping bag fitted with a small round tip (about 1/2 inch), and pipe rounds onto a parchment lined baking sheet (or silicone mat). You'll want to pipe them each about 1.75 inches in diameter. Give about 1.5 inches of space between each cookie, they will spread a tiny bit.

Once all shells are piped, gently tap your baking sheet against the counter a few times to remove any large air bubbles.

Let the sheet of piped cookies set until they set (until you can poke them softly without getting the batter on your finger). My rule of thumb is to let them set for at least an hour. This can vary depending on the moisture level in your kitchen.

Preheat your oven to 320°F. Once preheated, bake your macarons for 15-20 minutes. You'll know they're done by gently testing the top of the macaron. If it is still pretty soft, let bake for additional 2 minute intervals until it just barely moves from side to side when testing it.

Remove the sheet from the oven and let cool completely

Pair together cookies of same size. Ideally, you want them all to be the same size, but sometimes they can turn out a little wonky!

Melt marshmallows down (or use marshmallow cream), transfer to a piping bag, and pipe onto one side of the cookie. Sandwich it together with the other half, and continue this process until all of your macarons are finished.