Slice the garlic cloves. In a wide pan, cook the garlic on low heat, until they begin to brown. Remove the pan from the heat and let the oil cool.
When the oil is cooled, put the casserole back on a medium-low heat. Add the cod and cook slowly until it releases the gelatin it contains. Add the chilli pepper. It is very important that the olive oil isn’t hot, otherwise we will not be able to obtain the desired sauce. The secret to it is that we do not stop stirring, since it will cause the cod to release the gelatin. The sauce will thicken with the olive oil and garlic, forming a fine emulsion.
Serve the cod loins on a plate, with the pil pil sauce poured over it.