Bring a large pot of salted water to a boil and cook the pasta according to the package instructions until al dente. Before draining, reserve about ½ cup of the pasta cooking water. Set the pasta aside.
While the pasta cooks, place the bacon in a large skillet over medium heat and cook until crispy. Transfer the bacon to a paper towel-lined plate, then chop into bite-size pieces once cooled. Leave about 1 tablespoon of bacon fat in the skillet.
Add the diced shallot to the skillet and sauté for 2–3 minutes until softened. Stir in the minced garlic and cook for another 30 seconds until fragrant.
Add 1½ cups of the peas to the skillet and cook for about 2 minutes until warmed through. Transfer this mixture to a blender along with the basil, olive oil, Parmesan cheese, and about ¼ cup of the reserved pasta water. Blend until smooth and creamy. Taste and adjust salt and pepper as needed.
Return the cooked pasta to the skillet over low heat. Pour the pea sauce over the pasta and toss gently to coat. Add additional pasta water as needed to loosen the sauce and help it cling to the noodles.
Stir in the remaining ½ cup peas for texture and brightness if desired. Finish by topping the pasta with chopped bacon and extra Parmesan cheese. If you like a little heat, sprinkle in a pinch of red pepper flakes.
Serve immediately while warm.