Cook the macaroni in a large pot of rapidly boiling salted water as per packet instructions - add the peas when the macaroni has 3 minutes to go.
Lightly whisk (or use a fork) together the eggs, cream, and cheese in a bowl—season with salt and pepper.
Once the pasta and peas are cooked, drain and turn off the heat - reserving some of the cooking pasta water. Slowly pour ½ cup pasta water into the egg mixture and give it a whisk*.
Pour the sauce into the pot with the pasta and ham. Gently stir everything together for a few minutes until the sauce thickens slightly - make sure you work quickly and consistently as you don’t want the egg to scramble.
Serve immediately with extra cheese on top!
*To ensure the egg mixture doesn’t split, whisk vigorously as soon as the hot pasta water is added to the egg mixture until well incorporated before adding to the pot.