Preheat oven to 400 degrees. Poke the yams several times with a fork or knife to pierce the skin.
Place on foil or a sheet tray in the oven and bake for 1 hour.
Let yams cool for several minutes, cut in half and scoop out the fluffy insides (I love eating the high fiber skin as a snack).
Mash the yams with butter, maple syrup, evaporated milk and salt until creamy and fluffy.
Cut the oranges in half and slice a very thin disk from the bottom so they rest flat. The skins are actually going to be the “bowls”.
With a pairing knife cut around the inside rim of the orange removing the orange sections and pulp. Place any of the orange juice and pulp in a bowl and discard the white membranes and seeds.
Fill each orange cup with 1/4 cup of puree and top with several mini marshmallows (you can cover and refrigerate these overnight).
Preheat oven to 350 degrees.
Place on a sheet tray and bake for 20-25 minutes.