Peel the prawns. This takes awhile. Yawn.
Sprinkle the peeled prawns with chili powder, cayenne pepper, garlic powder and kosher salt. I suppose you want amounts. I don't know. Unfortunately my measuring standard for that was "until it looks right".
Toss the prawns to coat.
Saute prawns in half a tablespoon of melted butter. Do not overcook.
Melt 3-4 tbs butter in a sauce pan, over medium-low heat.
Add as many pressed or minced garlic cloves as you like. I use 3 or 4, usually.
Add a tablespoon of corn starch and a really good pinch of kosher salt.
Saute until you have a paste that is just barely starting to turn a little brown.
Add 2 pints of heavy cream.
Heat gently until sauce becomes bubbly and thickens.
Add two handfulls (or so) of grated parmesan cheese and half to 3/4 a can of tomato paste.
mix until cheese is fully melted and integrated into the sauce.
Prepare fettucine the the proper way: Lots of water, some salt in the water, al dente.
Combine sauce with noodles. Arrange noodles & sauce combination on a plate. Make a depression and place prawns in depression. Serve with grated parmesan. I'm told a chianti would go really well with this.
I recommend a green salad and a crisp vegetable on the side.