Bring a large pot of water to a boil. Salt generously and cook pasta until just shy of al dente (about 6 minutes). Reserve 1 cup of pasta water and drain the pasta.
While waiting for the water to boil and whilst pasta is cooking (Step 1), add the diced pancetta to a cold pan and place over medium heat and render out the fat.
Once the pancetta starts to crisp, add in the shallots, garlic, and jalapeno and cook until everything is soft and starting to brown on the edges and remove from the heat to a large bowl, rendered fat and all.
In a bowl, combine two eggs and one white (reserve the second yolk) with the parmesan cheese and black pepper. Whisk to combine.
Thin the egg and cheese mixture with about 1/4 cup of pasta water, whisking quickly to combine (so the hot pasta water doesn't scramble the eggs).
Add the cooked pasta to the bowl with the pancetta and toss to coat the noodles in the rendered fat.
Pour in the egg and cheese mixture, quickly tossing the noodles with tongs (again, to prevent scrambling), until the noodles are glossy. Thin the noodles out with pasta water to the desired consistency. Keep in mind that because the noodles are hot, they will quickly absorb all of the liquid so go for a slightly runny consistency and by the time the noodles are served (within a few minutes), they will be perfect.
Garnish the bowl with the reserved egg yolk, extra parmesan cheese, and parsley and present at the table. Give the pasta one final toss just before serving.