In a large pot, bring salted water to a boil. Add the whole wheat pasta and cook according to the package instructions until al dente. Once cooked, drain the pasta, reserving 1 cup of the pasta water for later use, and set the pasta aside.
While the pasta is cooking, heat the olive oil in a large skillet over medium heat. Add the diced onion and minced garlic, sautéing for about 3-4 minutes, or until the onion becomes translucent and fragrant.
Increase the heat slightly and add the lean ground beef to the skillet. Season the meat with salt, pepper, Italian seasoning, and red pepper flakes (if using). Cook for about 5-7 minutes, breaking it apart with a spatula until it’s browned and fully cooked.
Reduce the heat to low, and pour in the beef broth followed by the Greek yogurt. Stir the mixture continuously until it becomes creamy and uniform. If you prefer a thinner sauce, gradually add reserved pasta water one tablespoon at a time until desired consistency is reached.
Add the chopped spinach and halved cherry tomatoes to the skillet. Stir gently and cook for an additional 2-3 minutes, or until the spinach wilts down and the tomatoes soften slightly.
Carefully fold the cooked pasta into the skillet, tossing everything together until the pasta is well coated with the creamy sauce. Taste and adjust seasoning if needed, adding more salt or pepper as desired.
Spoon the creamy beef pasta onto individual plates or bowls. If desired, sprinkle grated Parmesan cheese on top for an extra flavor boost.
Notes
For an appealing presentation, serve the pasta in a large serving bowl, garnished with freshly chopped herbs like basil or parsley.