Set a prep bowl on your kitchen scale and sift in your almond flour. Make sure the sifted flour is 100g. Repeat this process with your powdered sugar (100g) and cocoa powder (10g). Weigh after your dry ingredients have been sifted. Whisk the almond flour, powdered sugar, and cocoa powder together. Set aside.
Start simmering 1-inch of water in a sauté pot large enough that you can set your stand mixer bowl into it without the bottom touching the bottom. Once it's come to a gentle simmer, set your bowl into the pot. Pour the egg whites and granulated sugar in, and begin whisking.
Whisk your egg whites until they are foamy and the sugar has dissolved completely. It should feel fairly warm like a nice bath, but should never be warmer than 160ºF.
Remove the bowl from the heat (NOTE: dry off the bottom of your bowl). Fit the bowl into your stand mixer, and turn it up to medium speed (4) until it thickens to the consistency of heavy cream).
Turn the speed up to medium-high (6) until your meringue JUST BARELY turns to stiff peaks. It will be very glossy and solid, but it will not look fluffy at all. You may not even believe it's stiff, but the tiniest peak counts. Test it by tilting the bowl. The meringue will not move even if turned upside down.
Fold in half of the dry ingredients until mostly incorporated. Fold in the second half of the dry ingredients. Continue folding the mixture together until it streams off your spatula like wet sand or lava. You should be able to trace a figure-8 with the batter streaming off your spatula.
Transfer to a piping bag fitted with a round tip. Onto lined baking sheets, pipe even circles. Refer to the post for the macaron baking mats I use. The batter should level out naturally within 10 seconds of piping. You should not have peaks or lumps. If you do, scrape it up and give it a couple quick folds before trying again. Make sure your mat is clean if you start over.
Once all the macaron batter has been piped out, heartily tap the pans against the counter 20-30 times to bring the bubbles to the surface. Use a toothpick to pop stubborn bubbles. The batter should fill back in on its own, but you can coax it along with your toothpick.
Allow your macarons to dry for 20-40 minutes. They should be dry enough that you can lightly touch them without any batter sticking to your finger.
While they are drying, preheat your oven to 310ºF. Your oven and climate may require you to bake your macarons as low as 295ºF or as high as 325ºF. It may take a few batches to find what works best for you.
Bake one pan at a time for 5 minutes. Turn the pan 180º. Bake for another 5 minutes. Rotate the pan again. Bake for another 5 minutes. Rotate once more (a total of 4 rotations) and bake for a final 5 minutes (for a total of 20 minutes. Repeat with your other pan (I usually need 2 pans for this recipe).
They should easily slide off the baking mat and not stick. Test one fresh from the oven. Sticking means they need another minute or two in the oven. Allow your macarons to cool completely on the baking sheet.
Chocolate Ganache
If needed, chop your dark chocolate bar. If using chocolate chips, skip this step.
Heat the cream in a small saucepan until wisps of steam begin to appear. Do not boil it.
Pour your hot milk over your chocolate in a heat proof bowl. Let it sit for 5 minutes.
Stir until there are no lumps and you have a nice smooth ganache. Stir in vanilla and salt.
Allow to cool completely. It will thicken up considerably. Transfer to a piping bag fitted with the tip of your choice. Save leftovers in the fridge, or sandwich between graham crackers for an extra treat.
Macaron Assembly
Turn half your shells upside down. Pipe a ring of chocolate ganache around the outside. Fill with a small dollop of almond pastry filling. I used about ¼ tsp per shell.
Set an unfilled shell half atop your decorated half, and very gently press to sandwich them together.