Whisk together all ingredients in a large bowl until sugar is dissolved, then pour through a fine-mesh sieve into a 1-quart glass measure. Divide custard evenly among cups, then transfer cups to baking pan. Bake in a hot water bath (
see Tips), pan covered loosely with foil, until custards are just set and a knife inserted in center of one comes out clean, 35 to 40 minutes.