Preheat the oven to 400°F (200°C). Prick sweet potatoes with a fork, place on a baking sheet, and roast until fork tender, about 45 to 55 minutes depending on size.
Let the potatoes cool slightly, then peel and transfer flesh to a large bowl. Reduce oven temp to 350°F (175°C).
Brown the butter in a small saucepan over medium heat until golden and nutty, about 5 minutes.
Mash sweet potatoes until smooth. Stir in the browned butter, half-and-half, brown sugar, eggs, honey, vanilla, cinnamon, nutmeg, ginger, and salt until fully combined.
In a medium bowl, combine the pecans, oats, flour, brown sugar, cinnamon, and salt. Add the melted butter and mix until mixture clumps into a coarse crumble.
Grease an 8x11-inch baking dish. Spread the sweet potato mixture evenly in the dish. Sprinkle crumble topping evenly across the top.
Bake at 350°F for 40 to 45 minutes, until the topping is golden and crisp. Let the casserole cool 10 minutes before serving.