Heat 1 tbsp oil in a large heavy-based pot over medium-high heat. Spread half the prawns in a single layer, sprinkle with salt and pepper. Cook for 1 ½ minutes, then turn and cook the other side for 1 minute. Remove into a bowl.
Add a touch more oil and repeat with the remaining prawns. Set aside and keep warm.
Turn the heat down to medium. Melt butter in pot, then add onion and garlic. Cook for 2 minutes until translucent.
Add wine, and stir, scraping the bottom of the pot to mix the brown bits from the prawn into the liquid. Bring to a simmer and cook for 2 minutes until the harsh alcohol smell is gone.
Add rice and stir for 30 seconds until rice is translucent on the edges.
Add about ⅔ of the chicken broth. Stir, bring to a simmer. Adjust the heat so it’s simmering gently.
Simmer for 5 minutes. Stir, then simmer for a further 2 minutes until broth is mostly absorbed and rice is visible on the surface.
Add remaining broth and milk. Stir, simmer for 3 minutes. Stir, simmer for 2 minutes.
Risotto should be soupy, and rice still a tiny bit undercooked.
Add peas and parmesan, quickly stir.
Taste, then add salt and pepper, and quickly stir.
Add Extra Butter, then stir vigorously for 10 seconds.
Lastly, gently stir through prawns (tip in any juices too).
Remove risotto from the heat; it should be porridge-like. To loosen, add hot tap water 2 tbsp at a time and stir through.
Give it a good final stir just before serving. Then ladle into bowls. Garnish with Parmesan and parsley if desired.
