1. Preheat the oven to 350°F and line two baking sheets with parchment paper.

2. In a large bowl, cream together butter and sugar until light and fluffy, about 3–4 minutes.

3. Beat in the vanilla and egg until fully combined.

4. Add flour, cocoa powder, baking soda, and salt. Mix until a soft dough forms.

5. Roll dough into 16 balls and place on prepared baking sheets.

6. Bake for 8–10 minutes, until edges are set and centers are slightly glossy.

7. Cool cookies on the pan for 10 minutes, then transfer to a wire rack to cool completely.

Mint Frosting
8. Beat powdered sugar, butter, milk, mint extract, and food coloring until smooth and fluffy.
9. Spread frosting evenly over cooled cookies. Freeze for 15 minutes.

Ganache
10. Microwave chocolate and oil in 30–40 second intervals, stirring until smooth.
11. Spoon ganache over chilled cookies. Let set before serving.