Halve the lobster tails lengthwise with kitchen shears and a sharp knife. Pull the meat out and refrigerate it. Set the shells aside.

Place the shells, 1 smashed garlic clove, bay leaf, and peppercorns in a 2-quart saucepan. Pour in the fish stock and bring to a gentle simmer over medium heat. Cook for 10 minutes, then strain through a fine-mesh sieve into a clean saucepan. Discard the solids. Keep the stock at a bare simmer on the lowest burner.

Melt 2 tablespoons of butter in a 12-inch skillet over medium-high heat. Add the 3 sliced garlic cloves and cook for 45 to 60 seconds until fragrant and just starting to turn golden at the edges.

Pat the lobster meat dry. Place it cut-side down in the pan. Sear for 90 seconds without moving until the edges turn opaque and light gold. Flip and cook for 60 seconds more. The meat should be just cooked through - it will finish later in the risotto. Transfer to a plate, tent loosely with foil, and set aside.

In a 4-quart heavy-bottomed saucepan, heat the olive oil over medium heat. Add the shallots and cook for 3 to 4 minutes, stirring occasionally, until softened and translucent.

Add the minced garlic and stir for 30 seconds until fragrant. Add the Arborio rice and stir for 2 minutes to coat each grain in oil until the edges look slightly translucent.

Pour in the white wine and stir until it is fully absorbed, about 1 to 2 minutes.

Begin adding the warm shell stock one ladle at a time (about 120 ml per addition), stirring almost constantly and waiting until each ladle is absorbed before adding the next. Continue for 18 to 20 minutes until the rice is al dente - firm at the center but not chalky - and the mixture flows slowly like loose porridge. You may not need all the stock.

Remove the saucepan from the heat. Add the cold butter cubes and grated Parmesan. Stir vigorously for 1 to 2 minutes until the butter melts fully and the risotto is glossy and thick.

Stir in the lemon zest and chopped parsley. Taste and season with salt and black pepper.

Fold in the reserved lobster meat gently or arrange the pieces on top. The residual heat will warm it through without overcooking it. Let the risotto sit for 2 minutes before spooning into wide shallow bowls. Garnish with a little extra parsley and serve immediately.