Preheat the oven to 350°F. Drain the canned crushed pineapple, keeping ¼ cup of juice for the recipe.
Wash then peel the sweet potato with a vegetable peeler. Chop into small pieces.
Add sweet potato to a bowl. Cover with water and bring to a boil. Reduce to let simmer until sweet potatoes are tender. Drain the water.
Add 3 cups mashed sweet potatoes to a bowl with 3 Tbsp butter, salt, and ¼ cup pineapple juice. Mash with a hand mixer or potato masher until smooth with no lumps.
Stir in the drained crushed pineapple.
Pour into a casserole dish and spread smoothly with a spatula. Dot the 1 Tbsp worth of butter on top.
Cut 10 marshmallows in half.
Place marshmallows on top of sweet potato. Bake for 40-50 minutes, or until marshmallows have turned golden brown. Let cool 10 minutes, serve and enjoy!
Recipe Notes:
Pineapple juice can be replaced with orange juice or milk.
Prep the mashed sweet potato the day before to help save time.
Drain as much crushed pineapple juice as possible from the can before adding to the sweet potato. Save the juice for the recipe.
Keep an eye on the recipe to see when marshmallows are starting to turn golden brown. The edges of the sweet potato may start to crisp as well.
If making a large meal, this whole recipe can be prepped in advance, stored in the fridge, then cooked right before you plan to serve.