Preheat oven to 375°F. Heat a skillet or griddle over medium heat until hot.

In a shallow pan or baking dish, whisk the eggs, half and half, salt, vanilla, cinnamon, allspice, and brown sugar until fully combined, about 1-2 minutes.

Spray the hot skillet or griddle with cooking spray.

Lay as many bread slices as will fit into the batter. Soak for 10-15 seconds, flip, and soak for another 10 seconds.

Lift the bread out, let the excess batter drip off, and lay it flat on the hot skillet.

Sear each side for about 2 minutes, until deep golden brown.

Transfer the seared slices to a baking sheet. Repeat soaking and searing with the remaining bread and batter.

Bake at 375°F for about 10 minutes, until puffed and set. Repeat until all slices are done.