In a large pot of salted water cook the spaghetti according to packaging directions.
In a large skillet melt 4 tablespoons of butter. Add the wine, garlic slivers, thyme and cream and cook until the wine is half evaporated, 5 minutes. Add the sliced tomatoes. Season with salt and pepper.
Season prawns with salt and pepper and add them to the skillet and cook them until pink and done, 5 minutes.
Drain pasta and add it to the large prawn wine sauce skillet. Add the remaining butter and continue cooking, 2 minutes until the butter melts, while gently stirring.