Prepare the tortellini according to package instructions, then reserve a cup of the cooking water and keep the tortellini warm or set aside with a little oil so they don't stick.
Heat the olive oil and butter in a large skillet over medium heat until the butter melts.
Add the diced onion and sauté until soft and translucent, about 3–4 minutes.
Add the minced garlic and cook for about 1 minute until fragrant.
Stir in the crushed tomatoes (including juices), salt, pepper, garlic powder, onion powder, red pepper flakes, thyme, oregano, cumin, dried basil, and raw sugar; bring to a gentle simmer and cook 5 minutes.
Add the fresh spinach all at once, cover the pan, and let it wilt, stirring occasionally; if the sauce becomes too dry, add up to 1/4 cup water at a time as needed.
In a small bowl, whisk the flour with the milk and heavy cream until smooth, then pour this mixture into the tomato and spinach sauce and stir to combine.
Stir in the grated Parmesan until melted and incorporated.
Use a slotted spoon to transfer the cooked tortellini to the sauce, gently fold to coat (add reserved pasta water a splash at a time if needed to loosen the sauce), and heat until everything is warmed through.
Serve immediately and top with additional Parmesan or fresh basil if desired.
