Blanch and refresh the garlic cloves in water three to four times.
Sweat chopped mushrooms and shallots in 50g of butter until soft.
Purée the remaining snail butter ingredients in a food processor until smooth.
Pass the purée through a fine sieve and mix with Parma ham, mushrooms, and shallots.
Roll the butter mixture in cling film and chill in the fridge until hard.
Simmer snails in water, skimming the surface as they come to a boil.
Add stock vegetables and bouquet garni and simmer gently for 3 hours.
Cool the stock slightly and strain through a muslin cloth, reserving the snails.
Finely shred the remaining Parma ham and thinly slice the fresh fennel.
Cook oats in simmering snail stock until all liquid is absorbed.
Remove oats from heat and beat in 70g of the chilled snail butter.
Sauté the cooked snails in a knob of butter and drain.
Toss sliced fennel with vinegar and walnut oil and season well.
Plate the porridge topped with ham, snails, and the fennel salad.