Creamy Pasta with Bacon and Peas

0 Defrost peas in the microwave until slightly warm. Drain off any excess water.
1 Bring a large stockpot of salted water to a boil. Add pasta and cook according to package directions. (Important: When pasta is almost done cooking, use a measuring cup to remove and reserve 1/2 cup of pasta water. You may need some of this to thin the sauce.)
2 While pasta is cooking, heat a large saucepan or skillet over medium heat. When hot, add bacon and sauté until golden and crisp, 8 to 10 minutes. Transfer bacon to a paper towel-lined plate.
3 Drain off all but a thin layer of bacon grease from the pan. 
4 Reduce heat under the pan to low-medium.
5 Add butter and shallots and saute until shallots are very tender, 2 to 3 minutes. 
6 To shallots, stir in peas and cook for 1 minute.
7 Move pan off heat.
8 Add pasta, crème fraîche, and lemon zest to pan and stir everything to combine. (Note: If the sauce is quite thick, add a bit of the reserved pasta water until sauce is creamy and smooth. I usually only need about a Tablespoon of water.)
9 Top pasta with cooked bacon, black pepper, and some parmesan cheese.