Step #1 Cook the first 4 ingredients in a medium saucepan over low heat/flame, stirring often, until butter melts; set aside & cool mixture to 100-110°.
Step #2 Stir the yeast, ½ c warm water, & 1 tbsps sugar in a 1 c glass measuring c; let mixture stand 5 mins.
Step #3 Beat sour cream mixture, eggs, yeast mixture, & 2 c flour at medium speed with a heavy-duty stand mixer until smooth.
Step #4 Decrease speed to low, & slowly add enough remaining flour (4-4 ½ c) until a soft dough forms.
Step #5 Turn dough out onto a lightly floured surface; knead until smooth & elastic (about 10 mins).
Step #6 Place in a well-greased bowl, turning to grease the top.
Step #7 Cover up & let rise in a warm place (85°), free from drafts, 1 hr or until dough is doubled in bulk.
Step #8 Punch down dough, & divide in half.
Step #9 Roll each portion into a 22x12 inch rectangle.
Step #10 Spread 1/3 c softened butter evenly on each rectangle, leaving a 1-inch border.
Step #11 Stir ½ c sugar & cinnamon together; sprinkle evenly over butter on each rectangle.
Step #12 Roll up each dough rectangle, jelly-roll fashion, starting at 1 long side.
Step #13 Place 1 dough roll seam side down, on a lightly greased baking sheet; bring ends of roll together to form an oval ring, moistening & pinching edges together to seal.
Step #14 Repeat with second dough roll.
Step #15 Cover up & let rise in a warm place free from drafts, 20-30 mins or until doubled in bulk.
Step #16 Bake in a 375° oven for 14-16 mins or until golden.
Step #17 Make glaze: stir this together the first 4 glaze ingredients; stir in the 2 tbsps milk, 1 tsp at a time, adding more milk, until spreading consistency.
Step #18 Slightly cool cakes on pans on wire racks (about 10 mins).
Step #19 Drizzle Creamy Glaze evenly over warm cakes, sprinkle with colored sugars, alternating colors & forming bands; let cool completely.