Heat olive oil in a large pot over medium heat. Add the diced onion and cook for 3–4 minutes until softened. Stir in the garlic and cook for 30 seconds until fragrant.
Add the ground beef and pork sausage. Cook, breaking up the meat, until browned and fully cooked. Drain excess fat if needed.
Stir in marinara sauce, diced tomatoes, chicken broth, Italian seasoning, red pepper flakes (if using), salt, and pepper. Bring to a rolling boil.
Add the broken lasagna noodles and cook for 10–12 minutes, or until noodles are tender, stirring occasionally to prevent sticking.
Reduce heat to low and stir in the spinach. Let it wilt for 1–2 minutes.
Taste and adjust seasoning as needed. Serve hot with a dollop of dairy-free ricotta or cottage cheese if desired.
