Bring a large pot of salted water to a boil over high heat. Cook the pasta for 8 minutes or just 2 minutes under the suggested cooking time. Drain well, reserving 1 1/2 cups of pasta water.
Meanwhile, heat a large straight-sided skillet over medium heat. Add the olive oil and pancetta. Cook, stirring often with a wooden spoon, until the pancetta is crisp, about 10 minutes. Add the black pepper and toast, stirring often, until fragrant. Add 1/2 cup of the pasta water to the pan and scrape up all the bits that are sticking to the bottom. Add the cooked pasta and sprinkle with the Parmesan. Add another 1/2 cup of the pasta water and stir to coat all of the pasta with the cheese. Add the pecorino and butter and stir to combine, creating a light, creamy cheese sauce. Add the peas and cook until warmed through. Add additional pasta water as needed to maintain the light sauce consistency. Serve with more grated Parmesan if desired.