In a small bowl, combine warm milk, yeast, and 1 tablespoon of the sugar. Let stand for 5 to 10 minutes, or until foamy.
½ cup whole milk, 2 ¼ teaspoons active dry yeast, ½ cup sugar
In a large bowl, whisk together flour, remaining sugar, salt, and cinnamon.
4 cups all-purpose flour, 1 teaspoon salt, 1 teaspoon ground cinnamon
Add eggs, melted butter, and vanilla extract to the flour mixture. Pour in the yeast mixture and knead for 8 to 10 minutes, until the dough is smooth and elastic.
½ cup unsalted butter, 2 large eggs, 1 teaspoon vanilla extract
Place dough in a lightly greased bowl, cover, and let rise for 1 to 2 hours, or until doubled in size.
In a small bowl, mix brown sugar, cinnamon, and softened butter to form a smooth paste.
½ cup brown sugar, 1 tablespoon ground cinnamon, 4 tablespoons unsalted butter
Roll the dough into a 10 by 20-inch rectangle. Spread the filling evenly over the surface.
Roll the dough tightly into a log and shape it into a ring, sealing the ends together. Place on a parchment-lined baking sheet. Cover loosely and let rise for 30 minutes.
Preheat the oven to 375°F (190°C). Bake for 25 to 30 minutes, until golden brown. Allow the cake to cool completely.
Whisk powdered sugar and milk until smooth. Drizzle over the cooled cake and immediately decorate with purple, green, and gold sanding sugar.
2 cups powdered sugar, 3 tablespoons milk, Purple, green, and gold sanding sugar