Preheat the oven to 425°F and prepare a sheet pan by greasing it with butter or nonstick spray.

Place sweet potato rounds on the pan, pour melted butter over them, and mix until the sweet potatoes are evenly coated.

Bake the sweet potatoes for approximately 20 minutes, then turn them over (the bottoms should be browned) and bake for another 15-20 minutes until they are soft when pierced with a fork.

Take the sweet potatoes out of the oven and switch the oven setting to broil.

Drizzle maple syrup over the roasted sweet potatoes and gently mix. Place marshmallow halves on top.

Broil the marshmallow-topped sweet potatoes for 1-3 minutes until they are lightly toasted (be careful not to let them burn).

Immediately after removing the sweet potatoes from the oven, press a pecan half into the top of each marshmallow. Serve promptly.