Follow the steps in order for the best result.
Begin by preheating your oven to 350 degrees Fahrenheit. This ensures the oven is properly heated when the cookies are ready to bake.
In a medium-sized mixing bowl, thoroughly whisk together the all-purpose flour, unsweetened cocoa powder, and fine salt. This blends the dry ingredients for a consistent cookie texture and flavor.
In a large mixing bowl, cream together the softened butter and granulated sugar using an electric mixer until the mixture becomes light and fluffy. This step is crucial for creating a tender cookie.
Add the room temperature egg and vanilla extract to the butter and sugar mixture. Beat until well combined, ensuring the egg is fully incorporated.
Gradually add the flour mixture to the butter mixture, mixing on low speed until just combined. Be careful not to overmix, as this can result in a tough cookie.
Roll the dough into 1-inch balls. Then, roll each ball in extra granulated sugar to coat completely. For a festive touch, consider using sanding sugar.
Place the sugar-coated dough balls onto baking sheets lined with parchment paper, spacing them about 1 inch apart to allow for spreading.
Bake the cookies for 5 minutes. Remove the baking sheets from the oven and gently create a thumbprint indentation in the center of each cookie. A melon baller or the back of a small spoon works well for this.
Return the baking sheets to the oven and bake for exactly 4 more minutes. The cookies may still appear slightly soft, but they will continue to set as they cool.
Remove the baking sheets from the oven and immediately press a Hershey's Kiss peppermint candy into the center of each thumbprint indentation.
Allow the cookies to sit at room temperature for a few hours to allow the chocolate kisses to set completely. This prevents them from melting and creating a mess.
Enjoy these delightful chocolate peppermint thumbprint cookies!