Prepare the Prawns: Start by heating a tablespoon of olive oil in a non-stick frying pan over medium heat. Add 2 cloves of minced garlic and let it sizzle until fragrant. Stir in the butter and wait until it begins to foam slightly. Add the prawns and cook for about 3 minutes, or until they change from black to pink and firm up. Transfer them to a plate and set aside.
Cook the Tagliatelle: According to the package instructions, cook the tagliatelle, then drain and set aside.
Make the Sauce: In a deep, high-sided skillet, heat the remaining olive oil over medium heat. Add the onion and the remaining garlic, cooking until soft and fragrant. Introduce the cherry tomatoes and cook until they start to soften and burst. Add the tinned chopped tomatoes and vegetable broth, bringing everything to a simmer. Let it simmer for 5-8 minutes, or until the sauce thickens enough to cling to the noodles. Remove from heat.
Incorporate the Spinach: Stir the spinach into the sauce, allowing the heat to wilt it.
Combine Pasta and Sauce: Add the cooked pasta to the sauce, tossing well to coat. Gently fold the cooked prawns back into the dish.
Serve: If it's casual pasta night, serve directly from the pan with tongs. For a fancier occasion, like date night, plate the pasta into bowls. Finish by topping with Parmesan cheese and chopped parsley or basil, as desired.