French Toast is best when eaten fresh. If you have any leftovers though, keep them in an airtight container in the fridge for up to 3 days and reheat on a griddle or in a frying pan over a low heat. Leftover custard can be kept in a sealed container or jar in the fridge for up to 4 days. It might thicken a bit but before you use it just add a drop or two of plant milk and give it a quick whisk before dipping your bread and cooking it.

1 cup plant-based milk 4½ oz / ½ heaping, very packed cup extra firm tofu (not silken) 2 teaspoons vanilla extract 2 tablespoons sugar , cane, turbinado or white (not brown or coconut sugar) ¼ teaspoon ground cinnamon ⅛ teaspoon salt 1 tablespoon OPTIONAL vegan butter **** , plus a little extra for brushing on the griddle/pan 6 thick (around 1 inch) slices crusty, sturdy, white bread , it should be a couple of days old

Add everything except the bread to a blender and blend until completely smooth.
Preheat a griddle or a pan over a medium/low heat.
Brush the griddle/pan with a little vegan butter (oil can be used instead but butter tastes better). Even if it's a non stick surface I recommend doing this as it makes it much easier to keep the golden crust that develops on the bread intact when turning it.
Pour the blended 'custard' into a wide bowl and dip the bread in it. Leave it to sit for around 20 seconds then turn over and leave for another 20 seconds. Make sure all areas are covered, then lift it out and quickly dip the crust around the edges.
Carefully place the custardy bread slices onto the preheated griddle or pan. Cook for around 4-5 minutes or until deeply golden, then flip carefully and cook for another 4-5 minutes on the other side, or until deeply golden. Try to leave it alone and not peek while it's cooking. If you move it too early the golden surface can get damaged and not look quite so pretty.
Remove from the pan and serve immediately.

Success Tips
Use stale bread. Fresh bread doesn't soak up the custard so well. It should be at least 2 days old. If you only have fresh bread, slice it up and leave it out on the counter for a few hours to dry out.
Use crusty bread and not cheap white sliced bread. Heartier bread holds it's shape better, it looks better, it tastes better and the crust part is lovely once cooked up in the custard.
Don't change any of the custard ingredients.
Blend the custard until absolutely smooth.
Don't leave the bread to soak for too long in the custard. 20 seconds each side is plenty. Any longer and it will get too soggy and you will risk breakage as you transfer it to the pan.
Use a really good non-stick pan to avoid sticking.
Cook until really golden.