Preheat an oven to 450 degrees F (230 degrees C). Prepare 4 baking sheets with cooking spray.
Stir together the olive oil and melted butter. Place the potato wedges in a large bowl; pour the butter mixture over the potatoes; toss to coat. Mix together the flour, bread crumbs, rosemary, garlic powder, onion powder, and salt; add to the potatoes and stir. Spread the potato wedges in single layers on the baking sheets.
Bake in the preheated oven until browned, occasionally moving the sheets around to assure even baking, about 45 minutes.