Combine the brown sugar, mustard and soy sauce in a large bowl or resealable container.
Reserve 1/4 cup of the marinade in a small container in the fridge.
Add the wings to the bowl or container and turn or toss to coat.
Cover and refrigerate for at least two hours (up to 12), turning every hour or so.
Preheat your oven to 375 F.
Line 2 large baking sheets with foil.
Lightly spray the foil with non-stick spray.
Remove wings from the marinade and place onto the foil. I like to turn the flats skin-side down for starters. Discard the marinade.
Bake for 30 minutes.
Flip the wings and baste with the reserved marinade. Bake another 30 minutes.
If desired, place the wings under the broiler for a few minutes to give them more color and to slightly crisp up the skin.
Serve.