Warm 1 cup milk in a saucepan until it's about 110 degrees – you don't want it too hot, or it'll kill the yeast and your dough won't rise properly. Your finger should fit comfortably in the pan; it should be the temperature of a warm bath.
Transfer the warmed milk to a medium bowl and sprinkle in 1 package active dry yeast. Let the yeast soften by letting it sit for about 2 minutes; stir in 3 tablespoons packed brown sugar and 1 cup flour with a wooden spoon. Dice 2 tablespoons butter and soften; stir into the mix. Add the remaining 1 1/4 cups flour and 1 teaspoon fine salt to make a sticky dough. Transfer the dough to the bowl of a freestanding mixer with a dough hook attachment and knead, adding more flour if needed, until smooth but still slightly tacky — this should take about 5 minutes. Shape into a ball, place in a lightly greased bowl and cover with plastic wrap. Let rise in a warm spot until doubled in size, about 1 hour.
Preheat the oven to 450 degrees and grease a large baking sheet. Punch the dough to deflate it, then turn out onto a lightly floured surface. (If the dough seems tight, cover and let rest until it relaxes.) Divide the dough into 6 pieces. Take one dough piece and stretch and fold one-quarter of the dough up to the opposite side of the dough, only pulling each segment to its maximum stretch. Repeat, working your way around the dough until it forms into a ball. Repeat until you have 6 dough balls.
Dissolve 1/3 cup baking soda in 3 cups warm water in a medium bowl. Place one dough ball on the slotted spoon and dip in the soda solution, submerging the dough for only a few seconds. Arrange each submerged dough ball on the prepared baking sheet, take a serrated bread knife and cut two deep slits in a cross on top of each bun. Sprinkle with pretzel salt.
Once all the dough balls have received a quick baking soda bath, bake for 10 to 12 minutes, or until a golden caramel brown.