Combine eggs, sugar, vanilla and cinnamon together and beat until combined (I use my immersion blender in a tall jar).
Melt a dab of butter in a large skillet over medium heat; don't be stingy with the butter!
Pour the French Toast mixture onto a large flat plate with a rim to contain it. Soak each slice on each side in the mixture and then place them in the sizzling butter.
Cook on medium for a minute or two depending on your stove until nicely browned.
Add some additional butter to your skillet and brown the other side.
Continue until all of the slices are finished; keep warm in a 200 degree oven if necessary, covered with foil.