Melt 1/2 cup of unsalted butter in a microwave-safe bowl. Combine with 1/2 cup granulated sugar and 1/2 cup light brown sugar, mixing until smooth. Add 1 egg and 1 tsp vanilla, blending until glossy, about 1-2 minutes.

Sift together 1 1/2 cups all-purpose flour, 1/2 tsp baking soda, and 1/2 tsp salt in a separate bowl. Gradually add to wet mixture on low speed until fully incorporated, forming a thick dough.

Gently fold in 1 cup of chocolate chips and 1/4 cup Halloween sprinkles using a spatula, ensuring even distribution without overmixing.

Scoop the dough using a 2-tablespoon cookie scoop onto a lined baking sheet. Cover with plastic wrap and chill in the refrigerator for 1.5 to 2 hours.

Preheat oven to 350°F (175°C). Arrange cookie dough balls on a baking sheet lined with parchment, spacing 2 inches apart. Bake for 11-13 minutes until edges are golden but centers are still soft.

Press candy eyes onto warm cookies as soon as they come out of the oven. Cool on the tray for 5 minutes before transferring to a wire rack to cool completely.