Preheat the oven to 350°F (175°C) and line two baking sheets with parchment paper.

Whisk together the flour, baking soda, and salt in a medium bowl.

Beat the softened butter, granulated sugar, and brown sugar until creamy and fluffy.

Mix in the egg, vanilla extract, peppermint extract, and green gel food coloring until smooth.

Gradually add the dry ingredients to the wet mixture, mixing just until combined.

Fold in the chocolate chips until evenly distributed throughout the dough.

Scoop approximately 1½ tablespoons of dough per cookie and arrange on the prepared baking sheets, leaving about 2 inches between cookies.

Chill the dough for 20–30 minutes if it feels too soft or sticky.

Bake for 9–12 minutes, until the edges look set and the centers remain slightly soft.

Immediately press candy eyeballs into the warm cookies to create monster faces.

Let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack.

Cool completely before storing in an airtight container or serving at your Halloween celebration.