Step 1: Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add the diced onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes.
Step 2: Add the minced garlic to the pot and cook for another minute until fragrant, being careful not to burn it.
Step 3: Pour in the vegetable broth, crushed tomatoes, dried oregano, dried basil, and red pepper flakes (if using). Bring the mixture to a gentle simmer, then reduce the heat to low, cover, and let it cook for at least 15-20 minutes to allow the flavors to meld.
Step 4: Increase the heat to medium-high and bring the soup back to a rolling simmer. Carefully add the potato gnocchi to the pot. Cook according to package directions, usually 2-3 minutes, or until the gnocchi float to the surface. Avoid overcooking.
Step 5: Stir in the heavy cream (or milk) and fresh baby spinach. Cook for another 2-3 minutes, or until the spinach has wilted completely and the soup is heated through.
Step 6: Remove the pot from the heat. Stir in the grated Parmesan cheese until melted and fully incorporated. Taste and adjust seasoning with salt and freshly ground black pepper as needed. Garnish with fresh parsley or basil and serve immediately.