4 slices (about 1/2 pound) gluten free brioche bread (See Recipe Notes)
2 eggs (100 g, weighed out of shell), at room temperature
1 teaspoon pure vanilla extract + vanilla bean seeds, if possible
1/2 cup (4 fluid ounces) whole milk, at room temperature
2 tablespoons (25 g) granulated sugar, plus more for sprinkling
1/4 cup (36 g) gum-free gluten free flour blend (24 g superfine white rice flour + 8 g potato starch + 4 g tapioca starch/flour)
1/8 teaspoon kosher salt
Unsalted butter, for frying
About the type of gluten free bread
I like to use our recipe for gluten free brioche bread to make French toast, sliced at least 1-inch thick. It has a tender, but relatively closed crumb, so it soaks up the custard really well without becoming very fragile.
But you can really use any sort of gluten free bread. In fact, commercially-prepared gluten free sliced bread is often great for French toast—especially if it’s gone a bit stale.
Begin by slicing the bread into slices about 1-inch thick, if possible. The bread should not be fresh out of the oven, or at all warm. Set the slices, side by side and not overlapping, on a large rimmed baking sheet or in a rectangular baking dish.
To make the custard, in a medium-sized measuring cup or bowl (ideally with a pour spout), place the eggs, vanilla and seeds, and about half of the milk. Whisk to combine well, beating the eggs until smooth. Add the 2 tablespoons granulated sugar, flour blend, and salt, and whisk until smooth and well-combined. Add the remaining milk, and whisk to combine.
Slowly pour the custard on top of the slices of brioche, allowing the bread to absorb as much of the custard as possible. Flip the bread over, and pour the rest of the custard onto the underside. Allow the bread to sit, flipping it occasionally, for about 30 minutes. Most of the custard should have been absorbed by the bread.
When the bread is nearly done soaking up the custard, place about 1 tablespoon of unsalted butter in a cast iron or other heavy-bottom skillet with at least 1-inch high sides. Turn the heat to medium-high, and heat until the butter has completely melted and is beginning to crackle in the pan.
Remove two slices (or as many as can fit without touching) from the custard and place them flat in the pan. Sprinkle the raw top of the slices of bread with a thin layer of granulated sugar. Allow the bread to cook, undisturbed for at least 3 minutes or until golden on the underside. Carefully flip the slices in the pan and continue to cook, sugar side down, for 4 more minutes or until golden brown on both sides. The sugar should have caramelized. Remove the slices from the pan and place on a plate for serving, sugar-side up. Repeat with the remaining slices.
To serve all the French toast at once or prepare it up to 20 minutes ahead of time, place the prepared slices, sugar-side up, on a clean, lined rimmed baking sheet. Keep warm in a 300°F oven until ready to serve.