Using a food processor, grind up your almond meal, powdered sugar, and espresso powder until it is a fine powder. Sift the mixture into a separate bowl.
Using an electric mixer, whisk the egg whites until they are foamy. While still mixing, gradually add sugar. Turn mixer on high until stiff white peaks form.
Add half of the powdered mixture to the eggs and use a rubber spatula to fold the powder in. You will want to do this with the fewest strokes possible to avoid losing the fluff of the meringue.
Add the remaining powder and carefully fold until completely incorporated. Again, make sure not to overmix. You want the consistency to resemble thick hot fudge.
Fit a piping bag with a round tip (I like to use a #10 Wilton) and fill the piping bag with your mixture. Pipe 1" round circles on a silicone baking pad (or parchment paper), leaving some space around them for spreading.
Leave the macarons sitting for at least an hour in order for the top layer to dry and create a shell. You should be able to touch the macarons without them sticking to your fingers. Depending on humidity, this may take longer than usual (one time, it took almost 3 hours). During this time, also preheat your oven to 270F and use the convection setting if applicable.
After they're hard to the touch, put them in the oven for 15-20 minutes. When you take them out of the oven, let them come to room temperature before attempting to remove the shells from the silpat. I found that it's easier to remove them if I roll the silpat (or parchment paper) away from the shells, rather than attempting to use a spatula to get them off.
Pipe whatever filler you want between two shells and then enjoy!