1. For the clarified butter: Clarify butter by melting in a skillet over medium heat. Continue cooking until butter is foamy on top. and set aside.
2. Allow solids to sink to the bottom and skim remaining solids from the top.
3. Pour off clarified butter from solids at bottom. (Yields 6 tablespoons of clarified butter)
4. Combine clarified butter, pistachios, shallots and pancetta in skillet over medium-high heat.
5. Stir until until pistachios are lightly toasted and shallots are translucent.
6. Remove from heat and add pasta, tomatoes, Parmesan cheese and parsley.
7. Toss to mix well.
8. Place back on heat for 5-10 minutes to melt the cheese.
9. Next, season with more parmesan cheese.