In a food processor, pulse mushroom until fine. Add torn bread slice and milk. Process until mixture it is paste-like. Set aside.
In a large pot, heat olive oil. Once oil is warm, add garlic and onions. Cook over medium heat unit garlic is fragrant and onions are almost translucent.
Add mushroom paste mixture. Stir to combine and cook for about 3-5 minutes until mushroom is cooked.
Add ground meat in chunks and stir to combine. Season generously with salt and pepper. Add red pepper flakes, dried oregano, and tomato paste. Stir to distribute.
Continue to cook until meat has browned. Then add diced tomato and crushed tomato. Stir to combine. Bring to a boil, then reduce heat to simmer. Cover pot and allow sauce to simmer for another 15-20 minutes. Check on sauce every 7 minutes or so to stir contents.
Taste sauce and season accordingly with more salt as needed.
Serve sauce warm over freshly cooked pasta. Serve with parmesan cheese and additional red pepper flakes for extra spice.