Mix warm milk, yeast, and 1 tsp sugar in a bowl and let sit until frothy, about 5 minutes.

Add eggs, butter, vanilla, and remaining sugar to the yeast mixture and whisk until smooth.

Gradually mix in flour and salt until a shaggy dough forms.

Transfer the dough to a floured surface and knead for 8–10 minutes until smooth and elastic.

Place the dough in a greased bowl, cover with a towel, and let rise in a warm spot for 1–2 hours until doubled in size.

Punch down the dough and roll it into a 10x20-inch rectangle on a floured surface.

Spread softened butter over the dough, then sprinkle evenly with brown sugar and cinnamon.

Roll the dough tightly into a log and shape it into a ring, pinching the ends together to seal.

Place the dough ring on a baking sheet lined with parchment paper and cover with a towel for a second rise of 30–45 minutes.

Preheat the oven to 350°F (175°C) while the dough rises.

Bake the cake for 25–30 minutes until golden brown, then let it cool completely on a wire rack.

Mix powdered sugar and milk to create a thick glaze, then drizzle over the cooled cake.

Sprinkle purple, green, and gold sugar over the glaze in sections and hide a plastic baby underneath the cake before serving.