In a large mixing bowl, combine the flour, granulated sugar, baking powder, cinnamon, and salt.

In another bowl, whisk together the milk, eggs, melted butter, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined.

Heat vegetable oil in a deep fryer or large pot to 350°F (175°C).

Use a donut cutter to shape the donuts from the dough and carefully place them in the hot oil.

Fry the donuts until golden brown on both sides, about 15 minutes. Remove and drain on paper towels.

In a separate bowl, mix the powdered sugar, 3 tablespoon milk, and 1 teaspoon vanilla extract to create the icing.

Divide the icing into three bowls and add food coloring to each (purple, green, and gold).

Dip the cooled donuts into the icing and let them set.