Preheat oven to 375℉. Spray 2 standard 12-cup muffin tins with cooking spray or line with paper muffin tin liners.
In a large bowl whisk to combine eggs, milk, sugar, and vanilla. Add bread and pineapple and toss to coat.
Divide mixture among muffin cups, filling them to the brim.
Bake until well browned and custard has set, 15-20 minutes. Let cool 5 minutes in the tins, then serve dusted with powdered sugar.