Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, cocoa powder, and salt. Set aside.
In a large bowl, cream the butter and sugar together until light and fluffy. Add the egg, vanilla extract, and peppermint extract, and mix until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.
Roll the dough into a log about 2 inches in diameter, wrap it in plastic wrap, and refrigerate for at least 1 hour.
Once chilled, slice the dough into 1/4-inch thick rounds and place them on the prepared baking sheet.
Bake for 10-12 minutes, or until the edges are firm. Allow the cookies to cool completely on a wire rack.
In a microwave-safe bowl, melt the semi-sweet chocolate and vegetable oil in 30-second intervals, stirring in between, until smooth.
Dip each cooled cookie into the melted chocolate, allowing any excess to drip off, and place them back on the parchment paper to set.

Once the chocolate has hardened, the cookies are ready to enjoy!
Variations & Tips
For a gluten-free version, substitute the all-purpose flour with a gluten-free flour blend. If you prefer a darker chocolate flavor, use dark chocolate instead of semi-sweet. For those who love a stronger mint flavor, increase the peppermint extract to 1 teaspoon. You can also add a sprinkle of crushed peppermint candies on top of the chocolate coating for a festive touch.