In a glass measuring cup or small bowl, stir together yeast, warm water, and sugar. Let it stand for 5 minutes until the yeast becomes foamy.

Add the sour cream, butter, sugar, and salt to a medium saucepan over low heat or in a microwave-safe cup. Heat until the butter melts. Remove from heat, and cool the mixture to 100° to 110°F.

In the bowl of a stand mixer with a dough hook, add the sour cream mixture, yeast mixture, egg, and half of the flour. Stir with a spatula, then mix on medium speed. Reduce speed to low and add remaining flour until a soft dough forms.

Knead the dough on low speed until smooth and elastic, about 10 minutes. The dough shouldn't be sticky or too dry. It should pull away from the sides of the bowl.

Place the dough in a lightly greased bowl and cover it with a linen cloth or plastic wrap. Let it rise in a warm place for about 1 hour or until it doubles in size.

Once risen, divide the dough in half.

Roll one portion into a long rectangle, about 16 inches long and 8-9 inches wide. Spread half of the softened butter on it, leaving a 1-inch border.

In a small bowl, mix the sugar and cinnamon together. Sprinkle half over the butter.

Roll the dough from the bottom up like a cinnamon roll and pinch the seam tightly.

Repeat with the other portion of dough.

To form the cake, place the dough rolls seam side down on a parchment-lined baking sheet. Pinch one end together, twist the dough logs, and bring the other ends together to form a ring. Seal the seam tightly.

Cover the cake and let it rise again in a warm place for 20 to 30 minutes, until doubled in size.

Preheat your oven to 350°F.

Bake the cake for 25 to 35 minutes until golden.

Once baked, allow it to cool most of the way.

In a large bowl, mix the glaze ingredients until smooth. Pour the glaze over the warm cake and sprinkle with colored sugars, alternating colors.

Let the cake cool completely, then serve.