Boil water (at least 2 liters) for pasta in wide shallow pan. Use 5 g salt per liter only
Whisk eggs and cheese in large glass bowl. Set aside
Cut pancetta into 1/2 inch cubes. Fry until starting to crisp. Remove from heat to cool and drain from grease reserving 2 Tsp of grease.
When water is heating, hold the bowl with egg mixture in the bain-marie and whisk for a minute or two until creamy and all cheese appears to be melted (about 150 deg). Set aside on stovetop to keep warm
Bring water to boil and add 5 grams salt for each liter of water. Add pasta and stir until it is covered by the water. Lower temp to simmer. Stir occasionally. Cook until done
Add 1/3 cup pasta water to egg mixture and whisk till creamy. Add the pasta to the egg mixture and mix vigorously. Add more pasta water if needed.
Add 2 tsp of the reserved oil, pancetta, pepper and mix
Serve topped with more cheese if desired and top with some chopped parsley