Heat milk until lightly warm to touch. Whisk in custard powder, sugar and ground cinnnamon (if using) and mix until combined. Pour this into a pie plate or other shallow bowl and set aside.
Roll the bread slices to flatten them a little using a rolling pin. Removing the edges is optional, I left them on mine.
Spread the filling (s) of choice on the bottom quarter of the bread and roll it into a tight roll.
Heat 2tbsp butter (I used Earth balance butter) in a skillet on medium heat.
Dip the bread roll in milk mixture, roll it around so that it absorbs milk evenly, then place seam side down in the preheated skillet. Cook until all sides are evenly browned, about 3-5 minutes on medium flame.
Remove and roll in cinnamon suagr for extra layer of sweetness and yumminess, I skipped this step as I felt my French toast were sweet enough. Enjoy right away with a drizzle of maple syrup.
Fresh Strawberry Filling: Crush ½cup of berries. Add water and cook in a small saucepan for 2 minutes. Sieve this mixture to get strawberry juice.
Mix corn starch and sugar; gradually add the berry juice to corn starch mixture and mix well. Cook this mixture on medium flame until it starts to thicken and becomes clear.
Add the cooked corn starch mixture to the remaining sliced strawberries, mix well and let cool completely. Use this to fill layer cakes or fill French toasts or use as topping on pancakes or ice creams.