How to Make It
Preheat oven to 400°F. Lightly coat an aluminum foil-lined baking sheet with cooking spray. Toss together sweet potatoes, olive oil, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper on the prepared baking sheet. Bake in preheated oven until sweet potatoes are just tender, 20 to 25 minutes, stirring halfway through.
Meanwhile, cook bacon, in batches, in a large skillet over medium until crisp, 10 to 12 minutes; remove bacon, and drain on paper towels, reserving 2 tablespoons drippings in skillet. Crumble bacon.
Remove potatoes from oven, and set aside. Reduce oven temperature to 350°F.
Cook onion in hot drippings over medium until just tender, 2 to 3 minutes. Add spinach, and cook until spinach begins to wilt, about 1 minute. Add bread cubes and crumbled bacon to spinach mixture, stirring to completely incorporate.
Whisk together eggs, half-and-half, Parmesan, and remaining 1 teaspoon salt and 1/4 teaspoon pepper in a large bowl. Stir in bread cube mixture, stirring gently to completely incorporate. Gently stir in roasted potatoes. Lightly coat a 13- x 9-inch baking dish with cooking spray; spoon mixture into prepared dish.
Bake at 350°F until golden brown and set in the middle, 45 to 50 minutes. Let stand 10 minutes before serving.