In a large bowl, whisk together eggs, sugar, and milk. Add cinnamon and nutmeg; whisk to combine.
Layer bread slices in a shallow baking dish and pour over egg mixture; let stand until bread begins to absorb liquid, 2 to 3 minutes. Turn bread slices and let bread absorb liquid on the opposite side, 2 to 3 minutes more.
Preheat oven to 200 degrees. Place a baking sheet or ovenproof serving platter in oven.
Working in batches, coat the bottom of a medium skillet with some of the clarified butter and heat over medium-high heat. Add 3 to 4 slices of soaked bread and cook until golden brown and crisp. Turn bread and cook until golden brown and crisp, adding butter as necessary to help browning and to give the French toast a nutty flavor. Transfer French toast to baking sheet in oven to keep warm. Repeat process with remaining clarified butter, soaked bread, and butter.
Serve French toast immediately dusted with confectioners' sugar, syrup, and fresh fruit or bacon, if desired.