In a large mixing bowl, combine melted butter with granulated sugar and light brown sugar. Blend until smooth and creamy, about 2 minutes.

Add the egg and vanilla extract, mixing until fully incorporated and the batter is light in color.

Gradually sift in the all-purpose flour, baking soda, and salt. Mix on low speed to combine.

Fold in the chocolate chips and Halloween sprinkles using a spatula, ensuring even distribution.

Scoop 2 tablespoons of dough onto a parchment-lined baking sheet, cover, and refrigerate for at least 1.5 hours.

Preheat the oven to 350°F. Bake dough balls for 11-13 minutes until edges are golden and centers are soft.

Press candy eyes onto warm cookies and cool on the baking sheet for 5 minutes before transferring to a wire rack.