Bring a large pot of salted water to a boil. Add the penne and cook according to package directions until al dente. Reserve about 1 cup of pasta water before draining. Set aside.

While the pasta cooks, heat olive oil in a large skillet over medium high heat. Add the ground turkey, breaking it up with a wooden spoon. Cook for 5 to 6 minutes, until no longer pink and starting to brown nicely.

Reduce heat to medium. Add the diced onion and cook for 2 to 3 minutes, until translucent and soft. Stir in the garlic and cook for another 30 seconds, just until fragrant.

Pour in the drained diced tomatoes, oregano, red pepper flakes (if using), and a generous pinch of salt and pepper. Let the mixture simmer for 3 to 4 minutes, allowing the tomatoes to break down and meld with the turkey.

Lower the heat to a gentle simmer. Stir in the heavy cream and grated parmesan cheese, mixing until the cheese is fully melted and the sauce is smooth and velvety. If it seems too thick, add a splash of the reserved pasta water to loosen it up.

Toss in the fresh spinach and stir until it wilts, about 1 minute.

Add the drained pasta to the skillet and toss everything together until every piece of penne is coated in that creamy sauce. Taste and adjust seasonings. Serve immediately, garnished with fresh parsley or basil and extra parmesan on the side.