Heat the olive oil in a large skillet over medium-high heat. Crumble in the ground turkey, spread it even, and cook 5 to 6 minutes until no longer pink, breaking it up as it browns. Transfer to a plate.

Reduce heat to medium, add the onion, and cook 3 to 4 minutes until translucent. Stir in the garlic for 30 seconds.

Pour in the crushed tomatoes and tomato paste. Add oregano, basil, salt, pepper, red pepper flakes, milk, and sugar. Stir, then return the turkey to the skillet. Bring to a simmer and cook on low for 15 minutes, stirring occasionally.

Meanwhile, cook the spaghetti in salted boiling water according to package directions until al dente. Reserve 1 cup of pasta water, then drain.

Add the drained spaghetti to the sauce and toss with tongs, adding a splash of pasta water if needed. Serve in bowls with plenty of grated Parmesan.