In bowl of a stand mixer fitted with a dough hook (or stir by hand), combine the brown sugar, milk, 2 1/2 cups of flour and the yeast. Stir until a soft dough forms, adding the remaining flour as needed (dough should be soft, but not really sticky). Turn out onto a lightly floured surface and knead to form a smooth ball.
Spray the inside of a large bowl with non-stick cooking spray. Transfer the dough to the bowl and cover with a clean dish towel. Allow to rise for about 2 hours until dough has doubled in size.
Turn the dough out onto a lightly floured surface. Punch it down and divide into 4 equal pieces. Start rolling and stretching each piece of dough to about 12 inches long. Cut into 1-inch pieces and transfer to a greased cookie sheet. Let rest, uncovered for about 30 minutes and preheat oven to 400 degrees.
Bring 6 cups of water to boil, then reduce heat to a gentle simmer. Boil pretzels in batches, cooking about 20 seconds on each side (they will be slightly puffed). Use a slotted spoon to transfer them back to the baking sheets. Bake until puffed and golden brown, about 15 minutes.
Brush warm pretzel bites with melted butter and sprinkle generously with kosher salt. Serve immediately.