When that's melted we add the onions, garlic, pinch of salt and cook that slowly until nice and soft about 10 minutes on medium heat (Don't let this colour or burn).
Add the white wine and reduce that down by half.
The minced alikreukel/periwinkle goes in followed by the cream. Simmer(NOT BOIL) this for about 15 minutes or until the cream has thickened slightly.
Take the pot off the heat and stir in the rest of the butter to emulsify.
Adjust the seasoning with some more sea salt, freshly cracked black pepper, fine grating of lemon zest and a little squeeze of lemon juice.
Serve this over some fluffy rice for the perfect seaside meal.
Notes
Once cooked it will keep in the fridge for up to 3 days or can be frozen for up to 6 months.