Create the Aromatic Broth: In a large stockpot (at least 8-10 litres), combine the 4 litres of water, 60g of Old Bay Seasoning, the quartered onion, the halved head of garlic, and the bay leaves. Squeeze the juice from the halved lemon into the pot, then add the squeezed halves as well. Bring the mixture to a rolling boil over high heat.

Cook the Potatoes: Once boiling, add the new potatoes to the pot. Reduce the heat slightly to maintain a steady, strong simmer. Cook for 10-12 minutes, or until the potatoes are just beginning to become tender when pierced with a knife.

Add the Sausage: Add the sausage chunks to the pot. Continue to simmer for another 5 minutes. The sausage will release its smoky flavour into the broth, adding another delicious layer.

Add the Corn: Gently place the corn pieces into the pot. Let them cook for 4-5 minutes. The kernels should be bright yellow and tender.

Cook the Shrimp: This is the final and fastest step. Add the raw prawns to the pot and stir gently. Cook for just 2-3 minutes. What works best for me is watching them closely; as soon as they turn pink, opaque, and curl into a 'C' shape, they are perfectly cooked. Do not overcook them.

Drain and Prepare to Serve: Immediately turn off the heat. Using a large slotted spoon or spider strainer, carefully remove all the solids (potatoes, sausage, corn, shrimp) and transfer them to a very large serving platter or a newspaper-lined table. Discard the onion, garlic head, bay leaves, and lemon halves from the pot.

Make the Butter Drizzle: In a small bowl, whisk together the melted unsalted butter, minced garlic, and a tablespoon of the remaining cooking liquid from the pot.

Garnish and Serve: Drizzle the garlic butter all over the shrimp boil on the platter. Garnish generously with chopped fresh parsley and serve immediately with the fresh lemon wedges on the side for squeezing.