Prep your bread. Slice into thick slices if the bread is not already sliced. Then, ensure the bread is somewhat stale (you can leave the bag open overnight before using). If not, toast the bread lightly.
On a plate with a lip, whisk together egg yolks, milk, and vanilla extract (see recipe card below for measurements). Dust the top of this mixture with cinnamon.
Dip each side of the bread into the mixture.
Pan fry the bread in a little bit of butter over medium heat until browned and toasted on both sides.