Melt unsalted butter in a microwave-safe bowl for about 30 seconds on high. Blend melted butter with granulated and light brown sugar until smooth and creamy. Beat in the egg and pour in vanilla extract. Mix until well combined.

In a separate bowl, whisk together flour, baking soda, and salt. Gradually mix this dry mixture into the wet ingredients until just combined. Avoid over-mixing.

Fold in chocolate chips and Halloween sprinkles until evenly dispersed.

Scoop 2-tablespoon portions of dough onto a lined baking sheet, spacing them apart. Cover with plastic wrap and chill in the refrigerator for 1.5 to 2 hours.

Preheat your oven to 350°F (175°C). Bake cookies for 11-13 minutes until golden edges and slight softness in the center.

Press candy eyes into each warm cookie after baking. Let cool on the baking sheet for a few minutes, then transfer to a wire rack to cool completely.