Prepare shrimp broth: Boil shrimp heads and shells with water and a vegetable cube for 15 minutes.
Cook the shrimp: Sauté shrimp halves in olive oil, season, and deglaze with ouzo.
Make the sauce: In olive oil, sauté onion, garlic, add tomatoes, tomato paste, bukovo, and the shrimp broth. Cook the spaghetti in this sauce until done.
Finish the dish: Add cooked shrimp, basil, and spring onion to the pasta. Serve with a drizzle of olive oil, fresh ground pepper, and basil leaves.