Fill a large pot with water, bring to a boil and salt the water. Add the pasta and cook to al dente, with a bite to it.
While the pasta is working, heat a large skillet over medium heat with the extra-virgin olive oil, 3 turns of the pan. Add the pancetta and cook until crisp, about 2 to 3 minutes. Remove the pancetta from the skillet with a slotted spoon to a paper towel lined plate to drain. Ser aside. Turn the heat on the pan back to low then add the sliced garlic and cook until golden brown, 4 to 5 minutes. Remove the garlic chips from the pan to drain alongside the crispy pancetta, reserve. Turn the heat up to medium again, add the crushed red pepper flakes and cook for 30 seconds. Add the roughly chopped escarole, tossing to wilt it in the flavored oil and wilting it into the pan in stages. Once all the escarole has fit into the pan, add the chicken stock, lemon juice, salt and pepper and cook for 2 minutes.
Drain the hot pasta well and add it to the escarole pan. Add lemon zest and toss to distribute. Turn the heat off and add the butter and cheese, toss to melt. Toss in the crispy pancetta and garlic chips. Serve the spaghetti with more cheese to pass at the table.