Using microwave, melt butter in a large bowl, then mix in sugars, vanilla, and salt until smooth and shiny. Beat in egg.
Whisk flour and baking powder together in a separate bowl, then fold into butter mixture.
Carefully mix candy into dough.
Roll dough into 16 equal balls. Place balls on a greased baking sheet at least 1 inch apart.
Gently press dough balls to flatten slightly. Then cover baking sheets and refrigerate cookies overnight.
Bake Cookies:
The next day, preheat oven to 375°F (190°C).
Bake cookies for about 15 minutes or until browned around the edges and on the bottom.
Let cookies cool on pan for 5 minutes, then transfer to a wire rack to finish cooling.
Serve cooled cookies right away or store in an airtight container. Enjoy!
Notes
Using melted butter and refrigerating the cookie dough before baking is what makes these cookies so thick and chewy.Check out the info before the recipe for tips on the best candy to use and more!