Rinse and dry chicken, then shake in flour mixture
Heat 1 tablespoon olive oil in a skillet over medium heat. brown chicken medallions slowly. After a few minutes add the butter. Remove chicken when cooked through, about 15 minutes (if medallions are thick as mine)
While chicken is cooking, cut up vegetables
Stir in pancetta, and cook until browned. Remove to paper towels.
Return skillet to medium heat and stir in onion, garlic, and crushed red pepper. Cook until soft, about 5 minutes. Stir in mushrooms. Cook until they begin to give off juices.
Turn the heat up to medium high, and pour in wine. Cook about 3 minutes.
Reduce heat to medium low. Stir in peas, cherry tomatoes, and spinach. Flake in tuna, drizzle in lemon juice, and season with salt and pepper. Stir to combine, and cook until warmed through.
Meanwhile, bring a large pot of salted water to boil. Cook penne until al dente, about 8 to 10 minutes. Drain, and stir into tuna mixture. Top with freshly grated Parmesan.