Warm the oven to 350°F (180°C), then cover a baking tray with parchment paper to ready it for baking. For extra-even baking, you can let the sheet warm in the oven for a minute before adding the cookies, it helps them spread perfectly.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth, light, and fluffy. This is the step that gives the cookies their soft, tender texture.
Add the room-temperature egg and vanilla extract, mixing until everything comes together in a creamy, uniform dough. Be sure to scrape down the sides of the bowl a couple of times so every bit of butter and sugar is fully incorporated.
In another bowl, whisk the flour, cocoa powder, baking soda, and salt. Gradually fold the dry ingredients into the wet mixture until you have a soft, slightly thick dough that’s ready to shape.
Roll the dough into balls, then roll each one lightly in granulated sugar for a subtle sparkle and a delicate, lightly crisp edge. Arrange them on the prepared baking sheet, leaving space between each cookie so they can spread evenly.
Bake for 8–9 minutes, keeping an eye on them. The tops should be puffy and slightly set. Don’t worry if they seem a bit soft, they continue to set as they cool on the sheet.
Let the cookies rest on the pan for about 4 minutes, then gently press a candy cane kiss into the center of each cookie. The chocolate will soften slightly.
Carefully place the cookies on a wire rack so they can cool down evenly and fully. Enjoy!