Pour the peas into a wide shallow bowl and cover with boiling water. Drain the peas once softened- they dont need to be hot.
Blitz the peas in a blender with the creme fraiche, mint leaves, garlic, lemon and olive oil. Use the pulse setting to retain a bit of texture. Alternatively reserve a third of the peas and add them whole.
Once blitzed to the desired consistency stir in the grated Parmesan and season with salt and pepper.
Cook the pasta according to the packet instructions then drain.
Put the pea sauce into the pasta pan and stir over a moderate heat for 30 seconds or so to take the chill off. Add the cooked pasta, mix well and serve in bowls with extra Parmesan.