Center a rack in the oven and place an overproof serving plate in the oven and preheat to 200 (F).
In a shallow dish, whisk together 1/2 cup whole milk, 3 large eggs, 1/3 cup dark brown sugar, 2 tablespoons honey, 2 tablespoons pure vanilla extract, 1 teaspoon ground cinnamon, and a pinch of kosher salt. Dip two slices of bread into the mixture.
Place a medium skillet over medium heat; place 2 tablespoons unsalted butter in the center of the pan and swirl to melt and coat the bottom of the skillet.
Once the mixture begins to soak through the bread, flip both slices. Allow to soak in the custard for 1 to 2 minutes. Place both slices of custard-soaked bread into the preheated skillet. Immediately place two more slices of bread into the custard to cook.
Once the bread is deeply golden on one side, flip and cook the other side. Flip the slices that are soaking in the custard too. Reduce the heat if you notice the bread browning too quickly.
Place the cooked pain perdu onto the preheated serving plate and return to the oven — this will keep the bread warm while you finish frying the remaining slices.
Place the remaining 2 tablespoons of butter in the skillet and repeat the process of melting and coating the pan. Repeat the process of soaking and cooking the remaining bread slices until all our golden.
Once all the bread slices are cooked, remove the plate from the oven and dust with powdered sugar. Serve immediately with vanilla-infused figs.