1. Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with butter or non-stick spray.
2. Place the peeled and cubed sweet potatoes in a large pot and cover with water. Bring to a boil over medium-high heat, then reduce to a simmer and cook for about 15-20 minutes, or until the potatoes are tender when pierced with a fork.
3. Drain the sweet potatoes well and return them to the pot. Mash them with a potato masher or fork until mostly smooth but still a bit chunky—this texture keeps the casserole interesting.
4. Stir in the melted butter, brown sugar, cinnamon, nutmeg, salt, milk, and vanilla extract into the mashed sweet potatoes. Taste and adjust seasoning if needed. This step reminds me of standing beside my grandmother, watching how she’d add just the right pinch of spice, making each bite burst with warmth.
5. Pour the sweet potato mixture into your prepared baking dish, spreading it out evenly.
6. Open the can of buttermilk biscuits and arrange them evenly on top of the sweet potatoes. You can leave them whole or tear them into halves for more biscuit coverage.
7. If you’re using nuts, sprinkle chopped pecans or walnuts over the biscuits for a crunchy, nutty finish.
8. Bake the casserole in the preheated oven for 20-25 minutes, or until the biscuits are golden brown and cooked through.
9. Remove from the oven and let it cool for about 5 minutes before serving. This resting time allows the casserole to set, making it easier to scoop out and share.

From my experience, the key to a perfect casserole is not over-mashing the sweet potatoes and keeping an eye on the biscuits as they bake. My kids always remind me when the kitchen smells “like magic,” and that’s usually when I know it’s almost done.