Melt the butter and allow it to cool for approximately 10 minutes.
Whisk melted butter, brown sugar, and granulated sugar until combined.
Add the whole egg and egg yolk and whisk until smooth.
Mix in vanilla.
In a separate bowl, whisk flour, baking soda, and salt.
Fold the dry mixture into the wet ingredients until nearly combined.
Fold in the chocolate chips and about ½ cup candy-coated chocolates.
Cover and refrigerate the dough for 30–45 minutes.
Preheat oven to 350°F (175°C) and line baking sheets with parchment.
Portion approximately 2 tablespoons or 40–45 g of dough per cookie.
Press reserved candy-coated chocolates and a few chocolate chips onto each dough ball.
Arrange cookies 2–3 inches apart.
Bake for 10–12 minutes, until the edges are set but centers remain soft.
Immediately press one, two, or three candy eyes into each warm cookie.
Cool on the baking sheet for 5–7 minutes.
Transfer to a wire rack to finish cooling.