I start by sifting the flour, cocoa powder, baking powder, salt, and cinnamon into a medium bowl. Sifting matters here because cocoa powder tends to clump, and you don't want cocoa pockets in your finished cookie. This only takes a minute, but it makes the dough much smoother later.
In a separate large bowl, I whisk together the sugar, melted butter, red gel food coloring, vanilla extract, and eggs until the mixture looks fully blended and evenly red. I make sure the butter isn't hot, since warm butter can start cooking the eggs slightly, which throws off the texture.
Next, I fold the dry mixture into the wet mixture just until no streaks of flour remain. I cover the bowl with plastic wrap and refrigerate it for at least 30 minutes. This chilling step firms up the butter again, which keeps the cookies from spreading too thin in the oven.
While the dough chills, I preheat my oven to 375°F and line two baking sheets with parchment paper. Getting the oven fully preheated before the dough goes in helps the cookies set their shape quickly instead of melting out flat on a lukewarm pan.
Once the dough is chilled, I scoop tablespoon-sized portions, roll them into balls, and roll each ball completely in the cookie crumbs. I space them about 3 inches apart on the prepared sheets, since they do spread a little as they bake.
I bake the cookies for 12 to 14 minutes, until they feel just slightly firm when I touch the top. I let them rest on the pan for 5 minutes before moving them to a wire rack to finish cooling completely.