Ingredients

Dough

• 4¾ cups plus 2½ tsp. (600 g) bread flour
• 1 ¼-oz. envelope active dry yeast (about 2¼ tsp.)
• 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt
• 1½ tsp. ground cinnamon
• ⅛ tsp. ground nutmeg
• 1 cup whole milk
• 4 Tbsp. unsalted butter, cut into pieces
• ¼ cup honey
• 1 large egg, beaten to blend
• Vegetable oil (for bowl)

Filling

• Bread flour (for surface)
• ½ cup (100 g) granulated sugar
• ½ cup (packed; 100 g) light brown sugar
• 1½ tsp. ground cinnamon
• 9 Tbsp. unsalted butter, room temperature, divided

Glaze and assembly

• 3½ cups (385 g; or more) powdered sugar, sifted
• ¼ cup (or more) whole milk, room temperature
• 1½ Tbsp. unsalted butter, melted
• 1 Tbsp. plus 1½ tsp. corn syrup (optional)
• ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt
• ½ tsp. vanilla extract
• ¼ tsp. almond extract (optional)
• Purple, green, and yellow or gold sanding sugar (for decorating)

Directions

Whisk 4¾ cups plus 2½ tsp. (600 g) bread flour, one ¼-oz. envelope active dry yeast (about 2¼ tsp.), 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, 1½ tsp. ground cinnamon, and ⅛ tsp. ground nutmeg in a large bowl to combine; set aside.

Heat 1 cup whole milk and 4 Tbsp. unsalted butter, cut into pieces, in a small saucepan over medium-low, stirring occasionally, until butter is just melted and milk is hot to the touch but not boiling, about 3 minutes. Pour into the bowl of a stand mixer fitted with the dough hook and add ¼ cup honey and ½ cup lukewarm water. Mix until combined, then let mixture cool until an instant-read thermometer registers 100°–110°.

Beat 1 large egg, beaten to blend, into milk mixture, then add reserved dry ingredients and mix on low speed until a dough forms, about 1 minute. Increase speed to medium and beat until dough is smooth and elastic and can stretch until it’s so thin you can see through it without ripping, 10–13 minutes (dough will be sticky). Transfer dough to a lightly oiled large bowl. Cover with a kitchen towel and let sit in a warm, draft-free spot until doubled in size, 1–2 hours.

Filling

Roll out dough on a lightly floured surface to a 24x16" rectangle, ¼"–⅛" thick. If dough springs back immediately when poked, let it rest 5 minutes to allow gluten to relax.

Whisk ½ cup (100 g) granulated sugar, ½ cup (packed; 100 g) light brown sugar, and 1½ tsp. ground cinnamon in a small bowl to combine. Add 7 Tbsp. unsalted butter, room temperature, and mix until a thick paste forms.

Spread filling evenly over dough, leaving a 1" border. Starting on a long side, tightly roll up dough into a log. Pinch seam closed with your fingers to seal. Flatten with rolling pin to ½" thick. Carefully transfer to a large cutting board and, using a pizza cutter or knife, slice log lengthwise into 3 strips. Transfer strips to a parchment-lined baking sheet. Braid together, starting from the top; leave ends untucked. Carefully join ends to form a ring and pinch together. Cover with a kitchen towel and let sit in a warm, draft-free spot until doubled in size, 1–2 hours.

Preheat oven to 350°. Melt remaining 2 Tbsp. unsalted butter in a small saucepan over medium or in a microwave-proof bowl in the microwave. Uncover dough, drizzle with butter; brush any butter that drips off back on. Bake cake until golden brown and an instant-read thermometer inserted into the center registers 210°, 40–45 minutes. Let cool.

Glaze and assembly

Whisk 3½ cups (385 g; or more) sifted powdered sugar, ¼ cup whole milk at room temperature, 1½ Tbsp. melted unsalted butter, 1 Tbsp. plus 1½ tsp. corn syrup (if using), ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, ½ tsp. vanilla extract, and ¼ tsp. almond extract (if using) in a medium bowl to combine. Glaze should be the consistency of brownie batter. Thin with more milk or add more powdered sugar if needed.

Spoon glaze over cake to coat. Sprinkle with purple, green, and yellow or gold sanding sugar, alternatingly so there are 2 sections of each color on the cake.