📖 Instructions

1. Before you even think about mixing, take your butter out of the fridge at least an hour beforehand. Seriously, room temperature butter is KEY for that perfect creamy texture. Also, make sure your eggs are at room temp too.
2. Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone baking mats. This prevents sticking and makes cleanup a breeze.
3. In a medium bowl, whisk together your dry ingredients: the all-purpose flour, unsweetened cocoa powder, baking soda, and salt. Make sure there are no lumps in the cocoa; you want a smooth, consistent mixture. Set this aside.
4. In a large bowl, using an electric mixer (either a stand mixer with a paddle attachment or a hand mixer), cream together the softened unsalted butter and granulated sugar on medium-high speed. Beat them until the mixture is light, fluffy, and pale in color, about 2-3 minutes. This step incorporates air and helps with that lovely texture.
5. Reduce the mixer speed to medium. Add the egg and the egg yolk one at a time, beating well after each addition until fully incorporated. Don't rush this; each egg needs to be fully blended into the butter mixture. Scrape down the sides of the bowl as needed to make sure everything gets mixed.
6. Now, add the vanilla extract and peppermint extract. Beat on low speed until just combined. Be careful not to overmix the extracts at this point.
7. With the mixer on low speed, gradually add the dry ingredients to the wet ingredients. Mix until *just* combined. As soon as you see no more streaks of flour, stop mixing! Overmixing develops the gluten too much, and we want tender, not tough, cookies. The dough will be thick and fudgy.
8. If you're using chocolate chips or chunks, fold them in now by hand with a spatula. You can also add crushed candy canes at this stage if you want them baked inside. For a crusted edge, we'll add them later.
9. Using a medium cookie scoop (about 1.5 tablespoons), scoop dough balls onto your prepared baking sheets, leaving about 2 inches between each cookie. These cookies will spread a bit, so give 'em room!
10. If you're opting for a super crunchy peppermint edge, gently roll the edges of each dough ball in a shallow dish of finely crushed peppermint candies or candy canes. Just the edges, mind you, so the center remains soft.
11. Bake for 9-11 minutes. The cookies are done when the edges are set and slightly firm, but the centers still look a little soft and slightly puffed. This is key for that chewy-center, crispy-edge combo.
12. Immediately upon removing them from the oven, if you desire extra crunch, sprinkle a few more crushed peppermint candies or candy canes over the warm cookies. The warmth will help them stick. Let them cool on the baking sheets for 5 minutes before carefully transferring them to a wire rack to cool completely. They'll firm up as they cool, so don't fret if they seem too soft at first.
13. Once completely cool, dust with a little powdered sugar, if you like, for that extra festive touch. Store them in an airtight container at room temperature for up to 5 days, though I bet they won't last that long! These babies freeze well, too, if you want to make a big batch ahead of time. Just make sure they're in a freezer-safe bag or container.