Put the pin oatmeal on a plate and dip the trout into it, covering thoroughly. Melt 2 tablespoons butter in a frying pan. Dip the trout into the butter and then into the pin oatmeal once again. Add the remaining butter into the frying pan and melt. Add the trout a fry quickly on both sides. Cover the base of a casserole with a little of the hot melted butter and lay the trout in it. Pour the remaining butter over and season with salt and pepper. Plate in the preheated 450 degree oven for 10 minutes. Remove the trout from the oven and serve garnished with a sprig of parsley and lemon slices.