In a medium saucepan, melt the butter, chocolate chips and chopped chocolate, stirring frequently, over medium heat. Let cool for 15 minutes.

In a medium bowl, sift together the flour, cocoa powder, baking powder and salt.

Using an electric mixer, beat the sugar, eggs and vanilla at low speed until smooth, 2 minutes. Mix in the cooled chocolate mixture just until blended.

Add the flour mixture in 3 batches, mixing on low speed until just combined.

Refrigerate the dough for at least 1 hour.

Preheat oven to 325 degrees F.

Spray two baking sheets with non-stick spray.

Using an ice cream scoop, scoop the dough and place on the baking sheets.

Arrange about 2 inches apart on each cookie sheet. They will flatten during baking.

Bake until the tops of the cookies crack, about 12 minutes.

Cut the marshmallows in half horizontally. Cut the Heath Bars in half too. Take 1/2 of the marshmallow and 1/2 of the Heath Bar and combine.

Remove the cookie sheets from the oven; gently press a the Heath Bar/marshmallow into each cookie (hide the Heath Bar underneath).

Bake until the marshmallows are just softened, about 4 minutes.

Allow cookies to cool a few minutes and then transfer to cooling racks to cool.

Serve and enjoy!