Adapted from The Meaning of Pie
Cook and then mash sweet potatoes until completely smooth. Sweet potatoes can be either cooked in the oven at 425 degrees for about an hour (until fork tender) OR by cut in to 1" pieces and boiled in water 20-25 minutes and then drain the water off.
Preheat the oven to 350 degrees. To the mashed sweet potatoes add the butter and brown sugar, eggs, vanilla and milk, and stir to combine. Then place the potato mixture into a 9"x13" casserole dish and smooth the top with a rubber spatula.
In a small bowl, combine the remaining brown sugar, flour, oats, and pecans. Add the melted butter and toss the mixture with a fork until combined.
Spread the topping evenly over the top of the casserole. Bake at 350 degrees for 30 minutes.
Servings 8