In the Morning (for an Overnight Timeline): At 8 AM, prepare the sourdough starter by combining the unactivated sourdough starter, all-purpose flour, and filtered water in a jar. Adjust the consistency as needed: if it’s too runny, add a few extra tablespoons of flour; if it’s too thick, stir in a tablespoon of filtered water. Watch the video for guidance.To help control the activation process: If you’ll be out all day, use cold water to slow the activation, or lukewarm water to speed it up.

In the Evening: At 7 PM, once the starter is activated, begin preparing the sourdough cinnamon roll dough.Melt the butter, then mix it with the cold milk until the butter cools down. Set this mixture aside for later use.

In the bowl of an electric mixer, combine the eggs, sugar, and activated sourdough starter. Once fully mixed, add the butter-and-milk mixture, stirring until well combined.Next, fold in the bread flour and sea salt, mixing thoroughly. Cover the bowl with a towel and let the dough rest for 35 minutes. At this stage, the dough will have a flaky texture.

Attach the dough hook to your electric mixer and knead the dough on low speed for 6 minutes. If the dough sticks to the sides, add a tablespoon of flour as needed. It will be a softer, less-tough dough, but it shouldn’t be sticky.Once kneaded, cover the dough with a towel and let it rest for another 45 minutes.After the resting period, stretch and fold the dough. Cover it again and leave it on the counter overnight. By morning, the dough should have doubled in size.

In the Morning: At 6 AM, place the dough onto a floured surface and roll it out with a rolling pin into a rectangular shape.*The dough will be ready to work with as early as 4 AM.

Melt the butter, then combine it with the brown sugar, granulated sugar, and cinnamon.

Spread the cinnamon sugar filling evenly over the dough. Make sure the filling is extra thick along the very bottom edge of the dough (this will become the center of the rolls). Sprinkle the flour and sea salt evenly over the filling.

Roll the dough into a long, tight log, then slice it evenly into 10 individual cinnamon rolls. Gently press each roll down to help keep the filling and dough tightly packed (you can see how I did this in the video).

Place the cinnamon rolls in the prepared baking dish. *For best results, use a glass baking pan coated in butter and lightly sprinkled with flour. This helps absorb any excess cinnamon sugar filling, turning it into a delicious caramel-like paste (instead of burning) that enhances the flavor of the rolls. I drizzle this sweet mixture over the top of the rolls immediately after baking.

Cover the cinnamon rolls and let them rise for 2 to 3 hours.

Bake the cinnamon rolls at 350°F for 45-50 minutes, or until golden brown and fully risen.*Place them on the middle rack to prevent burning on the top or bottom. If you’re baking multiple pans, alternate their positions in the oven every 20 minutes for even cooking.

As soon as the cinnamon rolls come out of the oven, drizzle the extra cinnamon sugar filling from the pan over the top. Let the rolls cool in the pan for 10 minutes before adding the buttercream icing.

Melt the butter and mix in the powdered sugar. Then add the milk and vanilla, stirring until smooth. *If the mixture is too thick, add a little more milk; if it’s too runny, add more powdered sugar until you reach your desired consistency. Evenly coat the cinnamon rolls with the buttercream icing.