In a mixing bowl, combine warm milk, active dry yeast, and a teaspoon of granulated sugar. Let this sit for 5-10 minutes until foamy.

In a stand mixer, combine remaining granulated sugar, eggs, butter, and salt. Pour in the activated yeast mixture and flour. Mix on low, then knead for 5-7 minutes.

Lightly oil a bowl, place dough inside, cover, and let rise until doubled, about 1 to 1.5 hours.

Mix brown sugar, ground cinnamon, and melted butter in a bowl until thick paste is formed.

Punch down dough, roll into a rectangle, spread filling, roll tightly, pinch seams, shape into a ring on a baking sheet.

Cover shaped cake and let rise until puffed, about 30-45 minutes. Preheat oven to 375°F.

Bake for 25-35 minutes until golden brown and hollow when tapped. Let cool on a wire rack.

Whisk powdered sugar, milk or water, and vanilla until smooth. Adjust thickness as needed.

Drizzle icing over cooled cake, sprinkle sanding sugars on while wet, and tuck in a small plastic baby if desired.