For the scampi, place the shrimp in a bowl with lemon zest and chopped garlic, season with salt and chill 30 minutes. Heat EVOO in large skillet over medium heat, add shrimp and cook to opaque, then add wine or vermouth. Add shrimp stock, then melt in butter (if using). Add pepper flakes, parsley and lemon juice; toss 1 full minute.
Have a mug or measuring cup on hand. Add shrimp to a medium bowl and toss with remaining garlic. Thinly slice a lemon and toss with shrimp. In the second skillet, heat EVOO, 2 turns of the pan, over medium-high and melt in 2 tablespoons butter. Add the shrimp mixture and toss 2 to 3 minutes; shrimp should be pink and opaque.
For the stock, toast shells in medium pot, add remaining ingredients and cook at a medium rolling boil to reduce to 1 cup, then strain. Season shrimp with garlic, zest, salt and pepper. Place a sage leaf down the back of each shrimp and wrap in pancetta.
In a separate bowl, beat the egg yolks, then add 1 large ladleful (about 1/2 cup) of the starchy cooking water. This tempers the eggs and keeps them from scrambling when added to the pasta. Drain the pasta well and add it directly to the skillet with pancetta and oil. Pour the egg mixture over the pasta.