01 -
Turn your oven to 400 degrees and let it preheat while you get the sweet potatoes ready.
02 -
Line a baking dish with parchment paper and place your sweet potatoes on it. Slide them into the oven and roast for a full hour until they're soft all the way through.
03 -
Let the potatoes cool down enough to handle, then peel off the skins. Put the potato flesh into a large bowl and add your maple syrup, melted butter, cinnamon, and a pinch of salt. Mash everything together until it's as smooth or chunky as you like it.
04 -
Spray a 9 by 13 inch baking dish with cooking spray. Scoop the sweet potato mixture into the dish and spread it out evenly so the top is nice and flat.
05 -
Pour the entire bag of mini marshmallows over the top. Press them down gently into the sweet potato mixture so they stick.
06 -
Put the dish on the middle rack of your oven and bake for 10 to 20 minutes. Watch it closely because marshmallows can burn fast. You want them golden and toasted, not charred.
07 -
Take it out when the marshmallows look perfect. Let the casserole cool for a few minutes before serving so nobody burns their mouth.