Use your recipe or follow my French Toast Recipe
to make the toasts. Once cooked, allow it to cool. Now you can any one of the following methods to freeze it.
Place a sheet of wax paper between each slice of French toast. Wrap the French toast stack tightly in aluminum foil or place inside a heavy-duty freezer bag and freeze. (Source
Lay it out on a very light greased cookie sheet and flash freeze it - that is, place the cookie sheet directly in a freezer for about 30-45 minutes till the toast slices are individually frozen. Remove them and stack/place them inside a freezer proof glass container or a heavy duty zip lock bag (remember to write the date on it). Should keep well for 1 to 2 months. When you want to cook it, use a toaster/microwave/oven or skillet and reheat it for 1-2 minutes.