Shrimp spaghetti with shell sauce

For the broth:

500 g shrimp with shells (medium or large) 2 tbsp olive oil 1 small onion, finely chopped 1 garlic clove, minced 2 tbsp tomato paste 50 ml white wine 500 ml water Salt Pepper

For the pasta:

400 g spaghetti 3 tbsp olive oil 1 garlic clove, finely chopped 100 g cherry tomatoes, halved 2 tbsp grated parmesan 1 tbsp butter 2 tbsp chopped parsley Salt Pepper