Heat the olive oil in a large skillet over medium-high heat. Add the onion and garlic and cook, stirring occasionally, until softened, about 5 minutes.
Add the oregano, basil, red pepper flakes, salt, and black pepper, and cook, stirring, for 1 minute.
Add the diced tomatoes and vegetable broth and bring to a simmer. Reduce the heat to low and simmer for 10 minutes.
Add the cauliflower florets and simmer until the cauliflower is tender, about 10 minutes.
Meanwhile, cook the spaghetti according to package directions.
To serve, divide the cooked spaghetti among four bowls and top with the cauliflower sauce. Sprinkle with Parmesan cheese, as desired.
Interesting Facts
Cauliflower is a nutritional powerhouse: it is low in calories and high in fiber, vitamins, and minerals.
This dish is an excellent source of vitamin C, vitamin K, folate, and potassium.
It is a delicious vegetarian dish, but can easily be made vegan by omitting the Parmesan cheese.