
Melt the butter in a large skillet. Add the onions and cook until slightly softened.
Add the garlic, basil, rosemary, and white wine. Simmer for 5 minutes.
Add the diced tomatoes. Cook for 10 minutes, until the tomatoes have softened.
Add the heavy cream. Gently simmer, stirring occasionally, until the sauce has thickened slightly, about another 10 minutes.
Remove from heat, and season to taste with salt and pepper. Serve over freshly cooked pasta.