Scrub potatoes; prick all over with fork. Bake on baking sheet in 400°F (200°C) oven for 45 to 60 minutes, or microwave at high for 10 to 12 minutes, or until tender when pierced with fork.
Cut off thin layer lengthwise from each potato; peel off skin from layer and place flesh in bowl. Using spoon; scoop flesh from bottom into bowl, leaving 1/2 inch (1 cm) thick shell. Add cheese, egg yolks and 1/2 tsp (2 mL) each salt and pepper; mash and set aside.
In separate bowl, beat egg whites until stiff peaks form. Using spatula, stir one-quarter into potato mixture until combined. Fold in remaining egg whites, bacon and chives. Mound back into potato shells. Bake in 350°F (180°C) oven for about 30 minutes or until tops are golden.