📖 Instructions

1. Begin by preheating your oven to 375°F (190°C). This ensures it's ready for both the sweet potatoes and the final bake. Lightly grease a 9x13 inch baking dish with butter or cooking spray; set aside.
2. First, prepare the sweet potatoes. Wash and peel 4 medium sweet potatoes thoroughly. Cut them into 1-inch chunks. This helps them cook more evenly and quickly.
3. Place the sweet potato chunks into a large pot. Cover them with cold water by about an inch. Add a pinch of salt to the water. Bring the water to a boil over medium-high heat, then reduce the heat to medium-low, cover, and simmer for 15-20 minutes, or until the sweet potatoes are fork-tender. You should be able to easily pierce them with a fork.
4. Once tender, carefully drain the sweet potatoes in a colander. Allow them to sit for a few minutes to steam dry. This step is important for preventing a watery casserole.
5. Transfer the drained sweet potatoes to a large mixing bowl. Add 1/2 cup (1 stick) unsalted butter, softened, 1/4 cup light brown sugar (packed), 1/4 cup granulated sugar, 1/4 cup milk (whole milk or half-and-half works best for richness), 1 teaspoon vanilla extract, 1/2 teaspoon ground cinnamon, and 1/4 teaspoon ground nutmeg. A tiny pinch of ground cloves is optional but lovely.
6. Using a potato masher, a fork, or an electric mixer on low speed, mash the sweet potato mixture until it is smooth and creamy. Make sure there are no lumps; we're going for a velvety texture here! Taste and adjust seasonings if necessary; you might want a little more sugar or spice depending on your preference.
7. Spoon the mashed sweet potato mixture evenly into your prepared 9x13 inch baking dish. Smooth the top with a spatula.
8. For the marshmallow topping: Evenly arrange 4 cups of miniature marshmallows over the sweet potato mixture. Make sure they cover the entire surface, creating a fluffy 'cloud' layer.
9. Place the baking dish into the preheated oven. Bake for 20-25 minutes, or until the sweet potato mixture is heated through and bubbling around the edges. Keep a close eye on the marshmallows during the last 5-10 minutes.
10. To achieve that perfect golden, toasted marshmallow top, you have two options: 1) If your oven has a broiler, switch it to broil (low setting). Watch it *very carefully* as marshmallows can burn quickly—this can take anywhere from 30 seconds to 2 minutes. Or 2) If no broiler, continue baking until marshmallows are golden. The goal is a light golden-brown, not burnt, puffy top.
11. Once the marshmallows are perfectly toasted, remove the casserole from the oven. Let it cool for 5-10 minutes before serving. This allows the casserole to set slightly and makes it easier to serve. Dig in and enjoy that comforting, sweet, and perfectly marshmallowy goodness!