How to Make It
Preheat broiler to high with oven rack in top position. Place sweet potato in a microwavable bowl; add water to a depth of 1/2 inch. Cover with a plate and microwave until slightly tender, 5 to 6 minutes. Drain sweet potato, and transfer to a plate. Pat sweet potato dry, and lightly coat with cooking spray.
Heat a 9-inch cast-iron skillet over medium-high. Add Canadian bacon and 1 tablespoon oil; cook, stirring often, until bacon is lightly browned, 4 to 5 minutes. Drain bacon on paper towels, reserving drippings in skillet. Add shallots and sweet potato to skillet; cook, stirring often, until lightly browned, about 5 minutes.
Whisk together eggs, Gruyère, sage, pepper, and salt in a bowl. Add remaining 1 tablespoon oil to sweet potato mixture in skillet; pour egg mixture into skillet. Cook over medium, gently pulling eggs in from sides of skillet with a spatula, until eggs are partially set, about 2 minutes. Sprinkle with goat cheese and reserved bacon.
Transfer skillet to oven; broil until eggs are completely set and toppings are golden, 3 to 4 minutes. Remove from oven; sprinkle with chives.