Prepare the Dough: Combine sour cream, butter, salt, and 1⁄3 cup of the sugar in a saucepan over medium-low. Cook, stirring, until butter melts, 5 minutes. Remove from heat; cool to 100°F to 110°F, 15 minutes.

Stir together yeast, water, and remaining 1 tablespoon granulated sugar in a 1-cup glass measuring cup; let stand 5 minutes.

Combine sour cream mixture, yeast mixture, 2 eggs, and 2 cups of the flour in the bowl of a heavy-duty electric stand mixer fitted with paddle attachment. Beat at medium speed until smooth, 1 minute. Reduce speed to low; gradually add 4 cups of the flour, beating until Dough forms.

Turn out onto a surface dusted with 1⁄4 cup of the flour. Knead, gradually adding remaining 1⁄2 cup flour, 2 tablespoons at  a time, until smooth and elastic, about 10 minutes. (It should be tacky but release easily from surface.) Place in a well-greased bowl; turn to grease top. Cover; let rise in a warm place (85°F) until doubled in bulk, 45 minutes to 1 hour.

Meanwhile, prepare the Praline-Cream Cheese Filling: Beat cream cheese, sugars, cinnamon, and vanilla with an electric mixer on medium speed until smooth. Beat in egg.

Prepare the baked cakes: Gently punch Dough down; divide in half. On a lightly floured surface, roll 1 portion into a 22- x 12-inch rectangle (keep remaining portion covered). Spread half of the filling over rectangle, leaving a 1-inch border. Sprinkle with 1⁄2 cup of the pecans. Starting at 1 long side, carefully roll up rectangle in a jelly-roll fashion. Place, seam side down, on a large parchment paper-lined baking sheet. Bring ends of roll together to form a ring. Moisten ends with water; pinch together to seal. Repeat with second portion and remaining filling and pecans. Cover; let rise in a warm place (85°F) until doubled in bulk, 45 minutes to 1 hour.

Preheat oven to 350°F. Uncover Dough rings, and bake in preheated oven until deep golden brown and done, about 25 minutes. Cool cakes completely on pans set on wire racks, about 1 1⁄2 hours.

Prepare the Creamy Vanilla Glaze: Stir together powdered sugar, melted butter, and vanilla. Stir in 3 tablespoons milk. Add additional milk, 1 teaspoon at a time, until pourable but still opaque. Pour evenly over cakes; sprinkle with sparkling sugars, alternating colors to form bands.