Feed your starter in a 1:1:1 ratio.

Right before reaching its peak, mix together the flours and water in a large bowl. Cover and rest 1 hour.

Add your starter. Mix until fully incorporated. Cover; rest 30 minutes.

Add in salt, and mix until the salt fully incorporated and the dough id smooth (3-5 minutes). Cover and rest 30 minutes.

Perform 1 stretch-and-fold; cover and rest 30 minutes.

Perform 3 FULL coil folds at 45 minute intervals.

After the final coil fold, cover the dough and let rest until the end of bulk fermentation (until doubled in size).

Turn the dough on a very lightly floured surface, divide into 6 small pieces, and perform your pre-shape (letter fold).

Cover and rest 15 minutes. Uncover, and do your final shaping.

Line a baguette pan or baking sheet with a kitchen towel; dust with flour. Place the loaves on top, cover, and place in the fridge overnight.

The next day, preheat the oven and dutch oven at 450F for 1 hour.

Invert the loaves on a piece of parchment paper, lightly dust with flour, and score. Place into the dutch oven, and drop 3 ice cubes under the parchment paper. Place the lid back on top.

Bake at 450F for 20 minutes with the lid on, and with a baking sheet placed on the rack below the dutch oven. Then, reduce the oven to 400F, remove the lid, and continue to bake for 15 more minutes.

Remove from the oven and dutch oven immediately. Let sit for at least 1 hour before slicing. Serve toasted with butter and flaky sea salt, or whipped honey cinnamon butter.

Place the butter in a medium bowl. Using a hand or stand mixer, beat on high for 2 minutes.

Then, add in the powered sugar, honey, cinnamon, and vanilla extract, and beat on high until well combined and fluffy. Save some at room temp to serve with the popovers. Then, transfer the rest to a jar or container and store in the fridge.