1. Combine milk, yeast, and 1/4 cup sugar in a bowl. Stir well, and set in a warm place for about 10 minutes. In another bowl, combine butter and next 3 ingredients; stir in 2 teaspoons lemon juice.
2. Combine flours, 2 teaspoons cinnamon, and kosher salt in a large mixing bowl. Add milk mixture and butter mixture, and beat, adding 1 to 2 tablespoons flour if dough is too sticky, until dough is smooth and forms a shaggy mass. (It should remain soft.)
3. Place dough in a well-greased bowl, turning to grease top. Cover with a kitchen towel, and let rise in a warm place (85°), free from drafts, about 1 hour.
4. Punch dough down, and place on a lightly floured surface. Roll dough into a 12- x 8-inch rectangle. Combine remaining 1 teaspoon cinnamon and 4 teaspoons sugar, and sprinkle evenly over dough. Roll dough into a log, and cut into 12 equal pieces. Places pieces into paper baking cups in a muffin pan; let rest 30 minutes.
5. Preheat oven to 375°. Brush cupcake tops with beaten egg, and bake 20 minutes. Remove from pan, and let cool on wire rack. Combine powdered sugar, water, and remaining 1 teaspoon lemon juice in a small bowl. Drizzle over cooled cupcakes, and top with sprinkles.
Recipe courtesy of Louisiana native David Guas of Bayou Bakery, Coffee Bar & Eatery in Arlington, Virginia