How to Make It
Make the blueberry orange sauce. Combine the cornstarch and 1 tablespoon water in a small bowl; set aside.
In a medium saucepan, combine the blueberries, sugar, and orange-flavored liqueur over medium-high heat. Stir in the cornstarch mixture. Bring to a boil; cook 1 minute, stirring constantly, until the sauce has thickened. Reduce the heat to low and keep warm.
Make the French toast. Whisk together the eggs, milk, sugar, vanilla, cinnamon, and nutmeg in a large bowl. Working one at a time, dip the bread slices into the egg mixture.
Melt 1 tablespoon butter in a large skillet over medium-high heat. Working in batches, add the bread slices to the skillet, two to three at a time, and cook until evenly golden brown, 1 to 2 minutes on each side. Reduce the heat to medium if the pan becomes too hot, and add butter as needed with each batch.
Serve immediately with warm blueberry orange sauce.