To make ahead and freeze, parboil, drain, rough the outside and transfer them to a baking sheet or dish in a single layer.  Loosely cover them with plastic wrap and freeze.  Once frozen, transfer to a freezer bag and return to the freezer. To roast from frozen, heat the olive oil in a large roasting pan for five minutes in the oven. Carefully add the frozen potatoes to the hot oil and turn to coat. Cook for 45-50 minutes, turning in the oil halfway through until golden and crisp.