1 large egg
2 Tbsp. unsalted butter, melted
3/4 cup milk
2 tsp. vanilla
2 Tbsp. sugar
1/3 cup all-purpose flour
1/4 tsp. salt
4-5 slices of day-old bread, 3/4 inch thick
unsalted butter for frying (1 Tbsp. per batch)
Heat a 10- or 12-inch skillet (preferably cast iron) over medium heat for 5 minutes. Meanwhile, beat the egg lightly in a shallow pan or pie plate; whisk in the melted butter, then the milk and vanilla, and finally the sugar, flour, and salt, continuing to whisk until smooth. Soak the bread without oversaturating, about 40 seconds per side. Pick up the bread and allow the excess batter to drip off; repeat with remaining slices.
Swirl 1 Tbsp. of butter in the hot skillet. Transfer the prepared bread to the skillet in a single layer; cook until golden brown, about 1 minute 45 seconds on the first side and 1 minute on the second. Serve the French toast immediately. Continue, adding 1 Tbsp. of butter to the skillet for each new batch.
Adapted from The New Best Recipe