Cut the croissant into 1/2" cubes. Transfer cubed croissant to a bowl, and toss with olive oil to coat.
Add dried oregano, grated parmesan cheese, and a pinch each of salt and pepper to the bowl. Toss to thoroughly combine.
Evenly spread the seasoned croissant cubes onto a baking sheet, and bake at 350 for 5 minutes. Remove the baking sheet from the oven, and carefully toss the croissant cubes with tongs (to help them toast evenly). Bake for another 3-5 minutes until slightly browned and crunchy.