Prepare the Dough:

• In the bowl of a stand mixer, combine warm water and brown sugar; stir until dissolved. Sprinkle yeast over the mixture and let sit for 5 minutes until foamy.
• Add melted butter and whole milk to the yeast mixture; stir to combine.
• Gradually add flour and sea salt, mixing with the dough hook attachment until a slightly tacky but firm dough forms.
• Knead the dough on medium speed for about 5 minutes until smooth and elastic.
• Place the dough in a lightly oiled bowl, cover with a damp towel, and let it rise in a warm place for 1 hour or until doubled in size.

Preheat Oven:

• Preheat your oven to 400°F (204°C). Line a baking sheet with a silicone baking mat or lightly grease it; avoid using parchment paper as it may stick.

Prepare the Baking Soda Bath:

• In a large pot, bring 4 quarts of water to a boil. Once boiling, carefully add the baking soda a little at a time to prevent overflowing. Reduce heat to a simmer.

Shape the Dough:

• After the dough has risen, turn it onto a lightly floured surface. Shape it into a tight, smooth ball by pulling the edges toward the center and pinching them together.

Boil the Dough:

• Gently place the shaped dough into the simmering baking soda bath, seam side down. Boil for 30 seconds, then carefully flip and boil for an additional 30 seconds.
• Using a slotted spoon, remove the dough from the bath, allowing excess water to drip off, and place it onto the prepared baking sheet.

Score and Bake:

• Brush the boiled dough with melted butter and sprinkle generously with coarse sea salt.
• Using a sharp knife, make a few slashes on top of the dough to allow for expansion.
• Bake in the preheated oven for 25-30 minutes, or until the bread is deep brown and sounds hollow when tapped on the bottom.
• Remove from the oven and let it cool on a wire rack before slicing.