In a large skillet, heat the olive oil over medium heat. Add the thinly sliced onion and bell pepper. Sauté for approximately 5 to 7 minutes, or until they soften and develop a light caramelization.
Introduce the ground beef (or turkey) to the skillet, breaking it up with a spatula as it cooks. Season with garlic powder, onion powder, salt, and pepper. Cook until the meat is thoroughly browned, about 8 to 10 minutes. Drain any excess fat.
While the meat mixture is cooking, steam the cauliflower florets in a separate pot until tender, around 6 to 8 minutes. Lightly mash the cauliflower with a fork or potato masher.
In a large mixing bowl, combine the cooked beef and vegetable mixture with the mashed cauliflower and softened cream cheese. Stir well until all ingredients are thoroughly mixed.
Lightly grease a 9x13 inch baking dish, then transfer the combined mixture into it, spreading it out evenly.
Generously top the casserole with the shredded provolone cheese.
Place the baking dish in the preheated oven and bake for approximately 20 to 25 minutes, or until the cheese is bubbling and golden brown.
Once baked, carefully remove the casserole from the oven and allow it to sit for about 5 minutes.
Before serving, garnish with freshly chopped parsley.