Sift together the flours and powdered sugar. Do this at least twice, I ended up doing it three times, twice to get it nicely combined, and once more.
Beat the egg whites until foamy. I used a stand mixer. Add the cream of tartar and continue to beat. It's important to not overbeat, but I think it's a lot easier to underbeat. You want lots of air. Add the sugar one tablespoon at a time and beat on medium-high until you get hard peaks like you were making meringue. Add a food coloring drop by drop until you get the color you want.
Sift the premixed dry ingredients into the egg whites (fourth sifting!). Gently fold it all together with a spatula. You want to mix it absolutely as little as possible to get it completely incorporated. You're trying not to deflate your meringue.
Put the mix in a pastry bag for piping out the shells.
Line 2 baking sheets, preferably with a nice silpat with macaron shapes on it, but you can also just use parchment and wing it. Pipe out about 25 rounds on each tray.
Gently-ish drop the trays a couple of times to get air bubbles out. Let the shells sit for a while. There seem to be a lot of different opinions on how long. I let them sit for a good 45 minutes. The idea is that they form a bit of a crust on the top, you should be able to touch them and not make a mark.
Preheat oven to 300F.
Bake for 18-20 minutes. It can be tricky to judge doneness. If you can pretty easily dislodge one from the sheet without it sticking or causing a mess, they are done.
Transfer to cooling racks.