Preheat oven to 450℉. Spray a 9x13 inch baking dish with olive oil or grease with butter.
Place your croissant pieces into the baking dish evenly and toast for 5 minutes. It's okay if they're overlapping. Remove from the oven and set aside.
Heat the olive oil in a large skillet over medium-high heat and sauté your spinach for 1-2 minutes. Transfer to a plate and dab with paper towel to absorb any excess moisture. Set aside.
Lower your oven heat to 350℉. In a blender, pulse together the eggs, milk, Boursin, salt, garlic powder and onion powder until smooth. Next, stir in with a fork the mozzarella, feta, spinach, scallions, dill and ham until combined. Then, pour this egg mixture evenly on top of your croissants. Use your hands to gently press everything down so that the croissants soak up the egg mixture. Cover the dish with foil and bake for 40 minutes. Uncover, increase the oven to 400℉ and bake for another 10-15 minutes or until golden brown on top.