Coarsely chop the Heath bars, set aside.

Melt the butter in a large glass mixing bowl in the microwave. Add the white sugar and brown sugar and beat with an electric mixer for 1-2 minutes at medium speed.

Add the egg and vanilla and beat for another minute.

In a separate bowl, whisk together the flour, baking soda, and salt. Stir into the wet ingredients. Fold in about half of the heath bar bits.

Roll the dough in balls and place on a plate. Cover and chill for 1-2 hours, or overnight.

Preheat your oven to 350°. Place the cookie dough balls at least 2 inches apart on cookie sheets lined with a silicone mat or parchment paper. (Or spray them with cooking spray.)

Bake cookies for 10-12 minutes, or until golden brown around the edges and set in the middle.

Immediately press a few Heath bar pieces into the tops of the hot cookies. Let sit on the pan for 3-4 minutes, then transfer to a wire rack to cool completely.