01 -
Arrange the marshmallows in a single layer on a plate or tray so they are not touching. Freeze for 1-2 hours until completely solid.
02 -
In a medium bowl, whisk together the flour, cornstarch, baking powder, and salt. In a separate bowl, beat the egg, cold milk, and vanilla. Pour the wet ingredients into the dry and stir until just combined; a few small lumps are fine.
03 -
Pour about 2 inches of vegetable oil into a heavy-bottomed pot or Dutch oven. Heat to 350°F (175°C) using a candy thermometer.
04 -
Working in batches of 3-4, drop frozen marshmallows into the batter and turn with a fork until evenly coated. For extra crunch, roll the battered marshmallows in graham cracker crumbs.
05 -
Carefully lower the coated marshmallows into the hot oil. Fry for 60-90 seconds, turning once, until the crust is deep gold and crisp.
06 -
Remove with a slotted spoon and drain on a wire rack or paper towels for a few seconds. Dust generously with powdered sugar while warm and serve immediately.