-
1
Place the rehydrated stockfish in a wide pan. Cover with cold water or light milk, add the bay leaf and garlic, and bring gently to a bare simmer. Poach for 30 minutes. The flesh is ready when it flakes apart with no resistance at the thickest point.
-
2
Lift the fish immediately from the poaching liquid. While still hot, break it apart with your hands, removing every piece of skin and bone. The flesh must go into the bowl warm — this is where the dish lives or dies: cold fish will not emulsify with the oil and will separate into greasy, broken chunks rather than forming a mousse.
-
3
Transfer the hot, flaked fish to the bowl of a stand mixer fitted with the paddle attachment, or work in a bowl with a wooden spoon. Begin beating at medium speed. With the machine running, pour the olive oil in the thinnest possible stream — little more than drops at first — so that the fish absorbs the oil as an emulsion. If using whipped cream, fold it in once all the oil is incorporated.
-
4
Stop beating when the mousse is light, white, and fluffy. It should fall slowly from a spoon but hold a soft mound when spread. Season with white pepper. Do not continue beyond this point: overworking drives the mousse toward a dense, paste-like consistency.
-
5
Grill the sliced polenta bianca rounds on a hot ridged pan or under a grill until golden on each side and faintly bitter at the edges. The surface should feel firm and dry to the touch, with clear char marks.
-
6
Allow the mantecato to cool to room temperature. Spread generously onto each polenta crostino. Lay a single flat-leaf parsley leaf on each. Serve immediately at room temperature.