Toss the sweet potatoes into the melted butter mixture then spread onto the prepared baking sheet in a single layer. Spread them out so they're not overlapping, if possible.
Bake for 10 minutes, remove from oven, use a spatula to flip the fries, then bake another 10 minutes.
Remove from oven, sprinkle with more salt (if you think they'll need it), let rest on the pan for five minutes, then serve.
Notes
Bake at 450°F for about 20 minutes total.
Flip halfway through for even crisping.
Baked fries are healthier than fried—retain more nutrients.