Boil tomatoes for 30 seconds, and then shock in ice water.
Peel the tomatoes
Cut into quarters and remove the seeds.
Slice into 1/8 inch slices.
Slice onion into 1/8 inch slices
Preheat a large sautée pan on medium heat. Pour 4 oz of clarified butter into the preheated pan. Put the sliced onions in to the pan. You want to sweat the onions till they have a translucent look.
Add tomatoes and garlic, and let it cook for 2 to 3 mins while mixing the tomatoes in with the onions.
Pour in the stock, and bring to a simmer. When it comes to a simmer, this is when you will add your whole butter and the white wine. Continue to stir the sauce, and add your chopped basil.
Reduce the heat to a low heat and let cook for 5 to 10 mins (stir occasionally). Add salt and pepper to season to taste, and top with Parmesan cheese. Bon Apetit! *Pasta should be ready*
Additonal Notes: the tomato Beurre blanc also goes great over croutons.