Bring a large pot of heavily salted water to a boil and cook pasta to al dente according to package instructions. Reserve 1/2 cup of the cooking liquid and drain.
Meanwhile, in a large skillet, cook pancetta over medium heat until beginning to brown, about 3 minutes. If the pan doesn’t have a good amount of grease in it (some pancetta has less fat than others), add the olive oil. Add shallot and garlic and cook for an additional 3 to 4 minutes, until shallot and garlic are translucent.
Turn the heat to low and stir in mascarpone, 1/4 cup of the reserved pasta cooking water, lemon zest, lemon juice, salt, and red pepper flakes. Stir until mascarpone is melted and a smooth sauce forms.
Stir in the pasta and swiss chard until the swiss chard wilts. If the pasta sauce is too thick, stir in small splashes of the reserved cooking water until it is creamy and sticks to the pasta.
Serve with a lemon wedge and grated Parmesan cheese
