Mousseline Nantua Recipe

Sweat aromatics and reduce

Melt 2 tbs unsalted butter in a small saucepan over medium heat. Add the finely chopped shallot and sweat until translucent but not browned, about 2–3 minutes. Pour in the white wine and simmer until reduced by roughly half (about 4–6 minutes).

Add stock and simmer

Add the fish stock to the pan and simmer gently for 8–10 minutes to concentrate flavor. Taste and skim any foam if necessary.

Finish with cream and crayfish butter

Stir in the heavy cream and return to a gentle simmer. Reduce heat to low and whisk in the crayfish butter (or lobster paste/tomato-lobster oil mixture) until fully integrated. Season with 1 tsp salt and 1/2 tsp white pepper. Keep warm over the lowest heat, stirring occasionally. If sauce is too thin, simmer a few minutes to thicken; it should coat the back of a spoon.

Bloom gelatin

Place 40 ml cold water in a small bowl and sprinkle 5 g powdered gelatin evenly over the surface. Let sit 5–7 minutes to bloom.

Temper egg yolks

Place the 4 egg yolks in a medium heatproof bowl and whisk lightly to loosen. Warm a small saucepan with 2–3 tbs water over medium-low heat to create a gentle bain-marie. Put the bowl of yolks over the simmering water (bowl should not touch water) and whisk gently for about 2–3 minutes to slightly thicken — you're bringing the yolks to about 60–65°C to cook gently for safety and body. Remove from heat.

Dissolve gelatin into yolks

Microwave the bloomed gelatin briefly (5–8 seconds) or warm it until liquefied, then whisk the dissolved gelatin into the warm egg yolks along with 1/2 tsp salt, 1/4 tsp white pepper, and 1 tsp lemon juice. Mix until smooth and homogeneous. Let cool slightly but not set.

Whip cream

Whip 250 ml cold heavy cream to soft peaks—it should hold shape but still be glossy. Reserve about 2 tbs of the whipped cream for folding into the shellfish sauce later if desired.

Fold to make mousseline

Fold one-third of the whipped cream into the egg-gelatin mixture to lighten, then gently fold in the remaining cream until uniform. Taste and adjust seasoning if needed. The mixture should be airy and smooth.

Incorporate seafood

Gently fold the chopped cooked crayfish or lobster into the mousseline, reserving a few pieces for garnish. If the mousseline seems too loose, chill briefly (5–10 minutes) to firm slightly before piping or spooning.

Prepare baking/serving vessels

Preheat oven to 160°C (325°F) if you plan to bake the mousseline briefly to set (optional). Lightly butter individual ramekins or a shallow gratin dish with the remaining 15 g butter.

Portion mousseline

Spoon or pipe the mousseline into the prepared ramekins, leaving a little space at the top. Smooth the surface with a spatula. If you prefer a lightly baked finish, place ramekins in a water bath (bain-marie) and bake at 160°C for 12–15 minutes until just set (center slightly wobbly). Otherwise, chill for 20–30 minutes to firm without baking.

Finish sauce and serve

Rewarm the Sauce Nantua gently. If you reserved 2 tbs whipped cream, whisk it into the warm sauce for added silkiness. Spoon 2–3 tbs sauce over each mousseline portion, garnish with reserved crayfish pieces and snipped chives, and serve immediately with lemon wedges on the side.

Storage and reheating

Leftover mousseline keeps refrigerated for up to 2 days (store sauce separately). Reheat gently in a bain-marie or warm oven (120–130°C) until just warmed through; avoid high heat or it will break.