• Pre-heat oven to 350 degrees and lightly spray a doughnut pan with cooking oil.
• In the bowl of a stand mixer or in a large bowl with hand mixer, beat butter and sugar together until light and fluffy, about 3 minutes.
• Add the egg and mix to combine.
• In a separate medium-sized bowl, whisk together flour, crushed Lucky Charms, baking powder, and salt.
• Stir dry ingredients into the butter sugar mixture, alternating with milk, until just combined. Stir in vanilla extract. Be careful not to over-mix.
• Evenly distribute batter into prepared doughnut pan, filling cavities almost all the way.
• Bake the doughnuts at 350 degrees for about 15 minutes, until doughnuts are starting to turn golden around edges and lightly spring back when touched.
• Let cool in pan for 5 minutes before removing to a wire rack to cool completely.
• Once cooled, frost doughnuts with marshmallow icing and top with Lucky Charms marshmallows.

Marshmallow Icing

• In the bowl of a stand mixer beat together egg white, corn syrup, and salt on high speed for 4-5 minutes until it thickens quite a bit and turns white.
• Mix in the powdered sugar, vanilla, and cream of tartar on low speed, until combined.
• Stir in hot water.
• Marshmallow icing can be stored in airtight container in fridge for about 10 days. This recipe makes enough to frost 4 batches of doughnuts.