In a saucepan heat the milk. In a small bowl make a flour paste, adding the flour and a small amount of water.
Add the flour paste into to heated milk, stir until the mixture has thickened.
Take the mixture off of the heat, and stir in the peas.
Cook the pasta to al dente as per packet instructions.
Once the pasta is cooked, strain and add to an oven-proof dish, pouring over the sauce.
Sprinkle over the grated cheese and put in the oven at 180C until the grated cheese is golden.