This bread, soaked in lime syrup, is a dessert specialty in Cuba.
In a large bowl, whisk together egg yolks and whole eggs. Add sugar; whisk to combine. Add evaporated milk, Grand Marnier, if using, vanilla, and cinnamon; whisk to combine. Divide mixture between 2 shallow baking dishes. Place bread in a single layer over mixture in dishes; let bread stand, turning several times, until soaked, about 15 minutes.
In a large skillet, melt half of butter over medium heat. Place soaked bread slices from one baking dish in skillet; cook until golden brown on both sides, 5 to 6 minutes per side. Wash and dry baking dish; return torrejas to clean baking dish. Wipe out skillet, and repeat with remaining slices and dish.
Pour 1 cup lime syrup over bread in each dish. Cover, and chill several hours or overnight, turning several times.
To serve, remove peel and pith from limes. Using a sharp knife, cut out lime sections; discard membranes. Garnish with lime wedges and remaining 1/2 cup lime syrup.