1/2 cup butter, room temperature
2 1/4 cups flour
2 1/4 teaspoons baking powder
1/2 teaspoon salt
1 1/2 cups packed dark-brown sugar
3 large eggs
1 teaspoon vanilla extract
1 cup miniature marshmallows
1 cup semi-sweet chocolate chips
1 cup white chocolate chips
1 cup butterscotch chips
18 soft caramel-candy cubes, coarsely chopped
Preheat oven to 350°F.
Lightly spray a 13x9-inch baking pan with no-stick cooking spray.
Line the pan with parchment paper, allowing a 2-inch overhang on the longer sides.
Spray parchment paper with no-stick cooking spray.
In a bowl, whisk together flour, baking powder, and salt.
Using an electric mixer, beat butter and brown sugar until fluffy.
Beat in eggs and vanilla.
On low speed, mix in flour mixture until combined.
By hand, stir in half of each of the marshmallows, chocolate chips, butterscotch chips, and caramels.
Spread the batter into the prepared pan.
Scatter remaining marshmallows, chocolate chips, butterscotch chips, and caramels on top.
Bake for 35 minutes, or until the top is golden brown and a cake tester inserted into the center comes out clean.
Cool on a wire rack.
Using parchment paper overhang as "handles", lift out of pan and transfer to a baking sheet.
Refrigerate until set, at least 30 minutes.
Cut into about 16 triangles.
Source: Adapted by LuAnn from Martha Stewart Cookies; posted by LuAnn for KRT.