Preheat griddle to 350 degrees F (175 degrees C). Spray the griddle with cooking spray.

Whisk eggs together in a bowl until smooth. Add half-and-half, vanilla extract, and cinnamon to eggs and whisk until frothy.

Dunk croissants, 1 at a time, into egg mixture just until both sides are coated.

Cook croissants on the hot griddle, split-side down, until golden brown, 2 to 3 minutes. Flip and continue cooking until second side is golden brown, about 1 minute. Repeat with remaining croissants. Sprinkle confectioners' sugar over croissants.