From Brunch by Marc Meyer and Peter Meehan
1 cup whole milk
1/2 cup heavy cream (or milk)
3 large eggs
1 teaspoon pure vanilla extract
1 vanilla bean, split and scraped
1 teaspoon ground cinnamon
1/4 cup bourbon
butter or neutral oil such as grapeseed, corn, or canola, as necessary
8 to 12 thick slices brioche, challah, or other bread
maple syrup, warmed
Set an ovenproof platter or a baking sheet with a cooling rack on top of it into the oven, and turn on the oven to 200 degrees.
Combine the milk, cream, eggs, vanilla extract, pod, and seeds, the cinnamon, and bourbon in a wide, shallow dish (a pie plate works great).
Heat a large cast-iron or nonstick skillet or griddle over medium-low heat for a minute or 2, then grease the pan with a teaspoon or more of butter, or if you prefer, oil. When the butter starts to sizzle (or, if you're substituting oil, when it slides easy from side to side) turn the heat up a touch.
Dip the bread into the batter, lightly coating each side, then gently shake off any excess batter and put the battered bread directly into the preheated pan. Cook the French toast 5 to 6 minutes in total, flipping once or twice, until golden brown. Transfer finished batches of toast to the platter in the oven. Repeat with remaining bread slices, adding more butter or oil to pan as necessary. Put your serving plates in the oven to warm before adding the last of the batter to the pan.
You can serve the French toast immediately, or hold it up to 30 minutes without any major degradation in quality. Serve with warmed maple syrup.