1. In a pot of boiling salted water, cook pasta as per packet directions. Drain the pasta 2 minutes before the suggested cooking time and reserve ½ - 1 cup of pasta water.
  2. In a large fry pan on a low - medium heat, heat the olive oil and fry the onion and garlic for five minutes or until fragrant and translucent. Stir occasionally to prevent the garlic from burning.
  3. In the same pan on a high heat, add the peas, chicken stock, lemon juice and a big pinch of salt and pepper and bring to the boil.
  4. Once boiling, take the pan off the heat and leave to slightly cool.
  5. Place the cooled mixture into a blender and blend until you have a silky smooth texture.
  6. On a low heat, place the sauce back into the fry pan with the lemon zest, cooked pasta shells and a splash of pasta water.
  7. Slowly incorporate the parmesan cheese and keep stirring until a thickened and glossy pasta sauce forms. Add more pasta water if needed.
  8. Take the pasta off the heat and finish off by stirring through the ricotta and sprinkling over fresh herbs.
  9. Serve and enjoy with family and friends!