Gratinéed Pollock Brandade

Cut the pollock into large chunks roughly 6 cm wide. Peel and chunk the potatoes. Mince 4 garlic cloves and leave the other 4 whole. Grate the gruyère, prepare the breadcrumbs, and zest and juice the lemon.

Place the pollock chunks in a wide saucepan with the whole milk, the 4 whole garlic cloves, bay leaves and thyme. Bring gently to a bare simmer over medium-low heat and poach for 8 minutes until the fish is just opaque and flakes easily. Check with a meat thermometer that the thickest piece has reached an internal temperature of at least 63°C before lifting the fish out with a slotted spoon. Reserve the poaching milk, discarding the bay and thyme.

Add the potato chunks to the reserved poaching milk and cook over medium heat for 18–20 minutes until completely tender when pierced with a knife.

Drain the potatoes, reserving the milk. Pass the potatoes through a ricer or fine-mesh sieve into a large bowl; discard the softened whole garlic cloves.

Warm the olive oil in a small pan over low heat with the minced garlic for 3–4 minutes until fragrant but not coloured.

Warm the double cream in a small saucepan over low heat until steaming but not simmering.

Flake the poached pollock into the riced potato, removing any remaining bones. Using a sturdy wooden spoon and working vigorously, fold in the warm garlic oil in a thin stream, alternating with the warm cream, until the mixture is smooth and just holds its shape — add a splash of reserved poaching milk if it feels too stiff. Season with nutmeg, lemon zest, flaky salt and white pepper, then taste and adjust.

Preheat the grill (broiler) to its highest setting. Lightly oil a 25 cm gratin dish and spread the brandade evenly, drawing gentle furrows across the surface with a fork to encourage browning.

Combine the grated gruyère and breadcrumbs and scatter evenly over the brandade. Drizzle with a little olive oil.

Slide the dish under the hot grill, 12–15 cm from the element, and grill for 8–10 minutes until the top is deep golden brown and the brandade is bubbling at the edges.

Remove from the grill, squeeze a little lemon juice over the surface and scatter with chopped parsley. Serve immediately with toasted sourdough or endive leaves.