In a large pot, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant, being careful not to burn it.
Add the diced tomatoes (with their juice), vegetable broth, Italian seasoning, salt, and pepper to the pot. Stir to combine.
Bring the mixture to a boil, then add the penne pasta. Stir well and reduce the heat to a simmer. Cover the pot and cook for about 10-12 minutes, stirring occasionally, until the pasta is al dente and most of the liquid is absorbed.
Once the pasta is cooked, stir in the chopped spinach and cook for an additional 2-3 minutes until the spinach is wilted.
If desired, stir in the grated Parmesan cheese until melted and well combined. Adjust seasoning with more salt and pepper if needed.
Serve hot, garnished with extra Parmesan cheese if desired.