1. For the pesto, combine the spinach, basil, walnuts, garlic, 1/4 cup cheese, oil, salt and pepper in a blender and puree.
2. Bring 7.5-quart wide stockpot of salted water to a boil. Add the pasta and cook according to package directions; drain.
3. Return the stockpot to the stove over medium heat and add the bacon. Cook, stirring occasionally, until the bacon is browned, 7-8 minutes. Add the garlic and cook until starting to brown, about 1-1 1/2 minutes. Stir in the peas and cook until bright green, about 2 minutes. Add the reserved pasta and cook until heated through, about 1-2 minutes. Remove from the heat and toss with the pesto. Divide among serving plates and serve with additional cheese if desired.