Rinse chicken inside and out. Drain well and pat dry with paper towels. Place chicken on a roasting pan, tempered glass or ceramic.
In a food processor or with a mortar and pestle, grind the garlic cloves and the peppercorns, making a paste. Place in a small bowl and incorporate the Madeira. Marinate, covered, in the refrigerator for at least 2 hours. Bring to room temperature before baking.
Heat oven to 375 degrees.
Pour the olive oil over the chicken. Place chicken in oven and bake 1 hour and 15 minutes, or until juices run clear. Let rest 15-20 minutes before carving.