Preheat the oven to 425°F (218°C) and coat a 2‑quart baking dish with cooking spray.
Heat 1 teaspoon olive oil in a large nonstick skillet over medium-high heat.
Add the sliced mushrooms, chopped onion, and chopped red bell pepper and sauté about 4 minutes until tender.
Add the chopped spinach, chopped fresh oregano, and freshly ground black pepper and sauté about 3 minutes until the spinach wilts; remove from heat.
Place the cottage cheese in a food processor and process until very smooth.
In a large bowl combine the processed cottage cheese, the sautéed vegetable and spinach mixture, hot cooked penne, shredded chicken, 3/4 cup shredded cheddar, 1/4 cup grated Parmesan, milk, and the can of condensed cream of mushroom soup; stir until evenly mixed.
Spoon the mixture into the prepared baking dish and smooth the top. Sprinkle with the remaining 1/4 cup cheddar and remaining 1/4 cup Parmesan.
Bake for 25 minutes or until the casserole is lightly browned and bubbly; let rest a few minutes before serving.