Spread a layer of oil, thyme and bay leaves on a sheet of baking paper. Place the prepared trout on top and stuff it with 3 thin slices of garlic, a handful of thyme and bay leaves, and a teaspoon of coarse salt, which will dissolve during cooking. Scatter the same ingredients used for the base over the trout. Wrap the fish in the foil and cook on a griddle over a medium-high heat for about 10–15 minutes on each side. Alternatively, bake in the oven for about 45 minutes at 180°C.
Remove the bones and serve at room temperature.