Prep the Bundt Pan:
Grease a large, 12-cup bundt pan with softened butter (about 3 tablespoons).
Dough:
In the bowl of a stand mixer, combine warm milk, water, sugar, melted butter, and yeast. Mix to combine and let sit for 5 minutes. Add flour and salt, mixing on low speed. Once the dough comes together, increase to medium speed and mix for 6-8 minutes until the dough pulls away from the sides, is tacky but not sticky, shiny, and smooth.
Transfer the dough to a large lightly oiled bowl, turning once to coat. Cover with plastic wrap and let rise until doubled in size, about 1 hour.
Cinnamon Coating:
Combine brown sugar and cinnamon in a medium bowl. Place melted butter in a separate small bowl.
Assembly:
Form the dough into an 8-inch square, cut into 64 pieces, and roll each piece into a ball. Roll each ball first in the melted butter, then in the cinnamon sugar mixture. Arrange the coated balls in the prepared bundt pan, layering and staggering. Cover with plastic wrap and let rise for 45-60 minutes until puffy.
Unwrap and bake at 350 F for 30-35 minutes or until deep brown and bubbly. Cool in the pan for 5 minutes, then turn out onto a platter. Cool for an additional 10 minutes before drizzling with glaze.
Glaze:
Whisk together powdered sugar, milk, and vanilla in a large liquid measuring cup until smooth. Pour over the slightly cooled bread.