1. Preheat your oven to 350°F (175°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 cold water. Bring to a boil over medium-high heat, then reduce to a simmer and cook until tender, about 15-20 minutes. You’ll know they’re done when a fork easily pierces through.
3. Drain the sweet potatoes and return them to the pot or a large bowl. Mash them until smooth but still a bit textured—my grandmother always said, “Don’t overdo it; you want a little bite left.”
4. Stir in the maple syrup, melted butter, milk (or cream), vanilla extract, cinnamon, nutmeg, and salt. Mix until everything is well combined and the mixture is creamy and fragrant.
5. Transfer the sweet potato mixture into your prepared baking dish, spreading it out evenly.
6. To make the pecan topping: In a medium bowl, combine the chopped pecans, brown sugar, flour, and cold butter pieces. Use your fingers or a pastry cutter to work the butter into the dry ingredients until the mixture is crumbly and resembles coarse sand.
7. Sprinkle the pecan topping evenly over the sweet potatoes.
8. Bake in the preheated oven for 25-30 minutes, until the topping is golden brown and the casserole is bubbly around the edges.
9. Remove from the oven and let it cool for about 10 minutes before serving. This rest time helps the casserole set and makes it easier to serve.

One of my favorite tips: if I’m making this for a holiday or special dinner, I often prepare the sweet potato base a day ahead and refrigerate it. Then on the day of, I just add the topping and bake. It saves time and keeps the flavors fresh.