Bring to boil a large pot of water. Add pasta and cook per packet MINUS 1 minute.
Just before draining, scoop out 1 cup of pasta cooking water and set aside. Drain pasta.
Meanwhile, melt 1 tbsp of butter in a large non stick skillet over medium high heat. Add prawns and cook for 1 1/2 minutes on each side until just cooked through. Remove prawns.
In the same skillet, add 1 tbsp butter. Once melted, add garlic. Stir for 20 seconds until fragrant.
Add wine and stir. Simmer for 2 minutes until wine mostly reduces.
Add cream, broth and parmesan. Stir until the parmesan is melted, then leave to simmer for 1 1/2 minutes until it thickens slightly (will thicken more in next step).
Add prawns, stir, then add pasta plus about 1/4 cup of reserved pasta water. Toss pasta (still on stove) and the sauce will thicken in about 30 - 45 seconds and start clinging to the pasta.
Take it off the stove before the sauce is as thick as you want - it will thicken more.
Sprinkle with most of the parsley and black pepper. Toss again until the sauce consistency is to your taste. Add a tiny splash of pasta water if it gets too gluggy.
Serve immediately, garnished with remaining parsley and parmesan if desired.