Dry peas are preferable for this recipe because during cooking they reduce to a cream and are sweeter than fresh peas. Moreover, as they do not have a skin around them, they are greener. Avoid cooking them on a high flame and use a saucepan with a non-stick bottom.
In a non-stick aluminium saucepan brown the butter with the onion. Add the dry peas and pour on the quantity of liquor. Add the stock and proceed to cook the peas until they are creamy. With a hand blender, mix to a smooth consistency without lumps. Add the milk and the Pecorino Romano cheese, remove from the heat and season with salt and pepper. Cook the pasta separately in boiling, salted water, then drain. Serve the pea velouté soup as an accompaniment to the pasta. Season with lightly toasted sesame seeds and a drizzle of olive oil, according to taste.