Activate the yeast by mixing warm milk with active dry yeast and letting it sit for about 5 minutes until frothy.

In a large mixing bowl, whisk together sugar, melted butter, eggs, and vanilla extract. Add the frothy yeast mixture and stir well.

In another bowl, combine flour, salt, cinnamon, and nutmeg. Gradually add this dry mixture to the wet ingredients, stirring until a soft dough forms.

Knead the dough on a floured surface for about 5-7 minutes until smooth and elastic. Place in a greased bowl, cover, and let rise in a warm place for 1-2 hours until doubled in size.

Punch down the dough, roll it out into a rectangle about 1/4 inch thick, and spread a thin layer of chocolate ganache over it. Roll tightly to form a log and shape into a circle.

Place the shaped cake on a greased baking sheet, cover, and let rise for another 30-45 minutes until puffy.

Preheat the oven to 350°F (175°C). Bake the cake for 25-30 minutes until golden brown. Allow to cool on a wire rack.

While the cake cools, prepare the ganache by heating heavy cream until simmering, then adding chopped chocolate and butter. Stir until smooth.

Once the cake is cool, pour the ganache over the top and sprinkle with colored sugar while the ganache is still wet.