Ingredients

• 2 tsp Active Dry Yeast (8 g)
• ¼ cup Whole Milk, room temperature (60 ml)
• 3 Tbsp Granulated Sugar (38 g)
• 4 Eggs
• 1 ¼ tsp Kosher Salt
• 3 ¼ cups Unbleached White All-Purpose Flour (406 g)
• 14 Tbsp Butter, at room temperature (200 g)

• 4 oz Bittersweet Chocolate, chopped into small pieces (113 g)
• 8 Tbsp Butter, at room temperature (113 g)
• 4 Tbsp Unsweetened Cocoa Powder (28 g
• 3 Tbsp Cinnamon
• ½ cup Powdered Sugar (60 g)
• ¼ tsp Kosher Salt

• 1 Egg
• 1 tsp Water

• ¾ cup Powdered Sugar (90 g)
• 1–2 Tbsp Whole Milk
• ¼ tsp Vanilla Extract

Instructions

1. Whisk together yeast and milk in the bowl of a stand mixer and let sit for 15–20 minutes, until slightly bubbly.
2. Add sugar, eggs and salt and whisk.
3. Add flour and, using the dough hook attachment, mix on low for about 15 minutes, stopping every 5 minutes to scrape the dough hook and sides of the bowl.
4. When the dough starts to come together and looks smooth, use the windowpane test to check for gluten development: pull out a small ball of dough and gently stretch it into a rough square.
5. When it is ready, it should stretch into a very thin, almost see-through sheet. If your dough feels strong and doesn’t tear during the windowpane test, it’s ready for the next step. If the dough easily tears and isn’t holding a windowpane, continue mixing and test it every few minutes. Scrape down the dough hook and the sides of the bowl. Cover and let rest for 10 minutes. This resting period allows the dough to relax and makes incorporating the butter much easier.
6. Return bowl to the mixer with the dough hook attachment and add about 3 tablespoons of butter. Mix on medium speed until the butter looks like it’s mostly incorporated. Continue adding butter in increments of about 3 tablespoons, scraping down the bowl and hook between additions.
7. After all the butter is incorporated, mix dough until it is smooth and pulls away from the sides of the bowl.
8. Place dough in a lightly greased covered container and let rise at room temperature for 20 minutes, then transfer to the fridge to continue to rise overnight.

1. Place chopped chocolate and butter in a microwave-safe bowl and melt in 5–10 second increments, stirring between each until the mixture is fully melted.
2. Add powdered sugar, cinnamon and cocoa powder and stir to combine.
3. Keep in a warm place. Microwave in 5-second bursts if it becomes too firm to spread.

1. Lightly grease two loaf pans and line with parchment paper slings.
2. Remove dough from the fridge and divide into two equal parts. Each half should weigh around 455 grams. Place one half of the dough back in the fridge while you shape the first one.
3. On a lightly floured surface, roll dough into a 10 x 10-inch square.
4. Spread with chocolate filling, leaving a ½-inch border, and roll the dough into a tight cylinder. Seal seam by pinching it all the way down.
5. If using two loaf pans, place log on a parchment-lined pan and place in the fridge. If using one pan and baking in two turns, proceed with the shaping steps.
6. Remove the second half of the dough from the fridge and repeat the steps for spreading and rolling into a log.
7. Place second log into the fridge and remove the first one to finish shaping.
8. Using a sharp knife, cut the log lengthwise from end to end, wiping off your knife as needed.
9. Gently turn both halves cut-side up and lay one half of the log over the other, creating an “X” shape.
10. Twist the two halves together, keeping the cut sides exposed, facing upward.
11. Pinch the ends together and gently lift the twist into the loaf pan. Gently wrap in plastic and set aside.
12. Repeat the steps for cutting and assembly with the second log of dough and wrap in plastic.
13. Let loaves rise in a warm spot until almost doubled in size, approximately 1–1 ½ hours. When gently poked, the dough should feel like a marshmallow and barely spring back.
14. Make the egg wash by whisking together the egg and water until smooth. Set aside.
15. When the loaves are almost ready, preheat the oven to 350°F.
16. Brush each loaf with egg wash and bake for 30–40 minutes, until dark golden brown and the internal temperature registers 195°F on an instant read thermometer.
17. Remove from oven and using the parchment paper sling, lift loaves out of the pan and onto another tray or cooling rack.

1. While the loaves are cooling, prepare the glaze. Whisk together all ingredients, then use a spoon to drizzle the glaze over the top of the loaves.
2. This cinnamon swirl bread is best eaten within 2 days. Store at room temperature wrapped in plastic or in an airtight container.