Boil pasta according to package directions in a large pot of salted water until al dente. Drain the pasta, reserving 1 cup of the starchy pasta water.
Meanwhile, in a large skillet set over medium-high heat, fry the bacon until golden and crispy, about 5 to 6 minutes. Transfer it to a paper towel-lined plate and drain off all but 1 tablespoon of bacon grease from the skillet.
Saute the onion in the grease left in the skillet until softened, about 3 to 4 minutes. Add the garlic and saute for 30 to 60 seconds, then add the peas. Saute about 2 minutes, until the peas have warmed and any frost melts off.
Stir in the cream and 1/4 cup of the reserved pasta water, brining the skillet to a simmer and cooking until the liquid is reduced by half. Add the Parmesan, a dash or two of pepper, and lemon juice, tossing well to combine.
Add the bacon and cooked pasta and toss, stirring in more of the reserved pasta water as needed to smooth out and thicken the sauce. Taste, season with salt and pepper, if necessary, and serve with more Parmesan on the side.