Melt butter in a small saucepan over medium heat.
Stir in brown sugar until it dissolves and looks glossy. This will make caramel base
Pour the caramel mixture into a greased 9×13 baking dish and spread it out.
Cut the French bread or brioche bread into bite-sized pieces
Scatter bread pieces evenly over the caramel layer.
In a bowl, whisk together eggs, milk, and vanilla until smooth
Pour custard evenly over the bread.
Press the bread down gently so that all even the top layer starts absorbing the custard right away.
Cover tightly with foil or a lid and chill overnight for the best texture
Remove from fridge 30-minutes before baking and preheat oven to 350°F.
Mix brown sugar and cinnamon, then sprinkle it evenly over the top.
Bake until golden and set, about 50 to 60 minutes. ( If the top browns too fast, cover it with foil for the last part of baking )
Once timer is up, pull from oveen and rest 15 to 20 minutes
Serve and enjoy