Preheat oven to 375°, and have a 13x9 pan ready.
Wash, peel, and dice sweet potatoes.
Place them into the pan.
Place the butter, cinnamon, nutmeg, brown sugar, flour, and pecans into a bowl and mix well.
Place topping over sweet potatoes. (or simply layer the butter then topping, and pecans)
Cover with foil.
Bake at 375° for 30-45 minutes or until sweet potatoes are tender when tested with a knife. You can keep them more firm or more soft depending on preference. I like them to hold the shape without being mushy, timing will also depend on how large you cut the pieces.
Continue to bake for 15 minutes uncovered, to crisp the topping.
*If cooking it straight from the fridge cook for 1 hour and crisp the last few minutes.
You can bake the sweet potatoes and remove them from th oven with the foil on, adn put it back in the oven to crisp the top a bit later if you need the oven space for other items.