Beat the eggs, milk, vanilla sugar and cinnamon in a bowl. Pour the mixture into a deep bowl or plate.
Dip the slices in the mixture. Make sure they are well coated on both sides. Usually 1 minute per side is enough, but it depends on how old (and dry) the bread is.
Heat some butter in a frying pan and fry the French toast until cooked and golden brown on both sides. We always make it in rounds here so everyone can eat it warm and fresh, which is when it tastes the best.
Tips
Serve French toast with fresh red fruit and extra powdered sugar or maple syrup. It tastes even better.
How to store
I do not recommend storing French toast because it simply does not taste good. So do not make more than you are going to use.