Heat olive oil in a large deep skillet or pot over medium heat.
Add the chopped onion and cook for 3-4 minutes until softened and translucent.
Add the minced garlic and cook for another 1 minute until fragrant.
Pour in the canned diced tomatoes, vegetable broth, and heavy cream. Stir to combine.
Add the dried oregano, dried basil, salt, and black pepper. Stir well.
Add the tagliatelle pasta to the pot, making sure the pasta is submerged in the liquid.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered.
Cook for about 12-15 minutes, stirring occasionally, until the pasta is tender and most of the liquid has been absorbed.
Remove from heat and stir in the grated Parmesan cheese until melted and creamy.
Serve immediately garnished with fresh basil leaves.