Have a stock pot of water near boiling before starting the sauce for this recipe! If you're fast at making the sauce, throw in ravioli when you begin to make the sauce. If not, cook ravioli according to package directions.
In a large saucepan, melt 1/4 cup of butter or margarine over a medium heat. Saute garlic for 1 to 2 minutes. Stir in olive oil and capers. Add 4 ounces of white wine and prawns, and bring to a boil.
Reduce heat and simmer for 2 to 3 minutes, letting wine reduce. Stir in sliced mushrooms, and additional butter and wine so that the sauce is thick, but still liquid after 2 to 3 minutes. Stir in lemon juice, and add fresh pepper to taste.
To serve, place raviolis on 4 plates, then place 5 to 6 prawns on each plate. Evenly distribute the remaining sauce between the four plates, and garnish with lots of freshly grated parmesan cheese!