In a small bowl, combine warm milk, active dry yeast, and a teaspoon of granulated sugar. Allow the mixture to sit for about 5–10 minutes until it becomes foamy.

In a large mixing bowl, combine the remaining sugar, eggs, softened butter, and salt. Gradually pour in the activated yeast mixture and add flour and ground cinnamon. Knead the dough for 5–7 minutes until smooth.

Lightly grease a large bowl, place the dough inside, cover with a damp cloth, and let it rise in a warm area for about 1 to 1.5 hours until doubled in size.

Prepare the filling by mixing brown sugar, ground cinnamon, and melted butter in a bowl until it forms a thick paste.

Once the dough has risen, punch it down, roll it out into a rectangle, spread the filling evenly, roll it tightly, and seal the seams.

Place the formed ring on a parchment-lined baking sheet, cover loosely with a damp cloth, and let it rise again for 30-45 minutes. Preheat the oven to 375°F (190°C).

Bake the King Cake for 25-35 minutes until golden brown. Let it cool completely on a wire rack.

Whisk together powdered sugar, milk or water, and vanilla extract for the glaze. Drizzle it over the cooled cake and decorate with sanding sugars.