Whisk warm milk, sugar, and yeast in a large bowl. Rest 5 minutes until foamy.
Stir in melted butter and salt. Add most of the flour and mix into a shaggy dough.
Knead on a lightly floured counter 5–7 minutes, adding flour as needed, until smooth and soft.
Place dough in a greased bowl, cover, and let rise until doubled, 45–60 minutes.
Make caramel: Melt butter in a saucepan. Whisk in brown sugar, cream, and corn syrup.
Simmer 2–3 minutes until glossy. Stir in salt and remove from heat.
Pour caramel into a greased 9x13-inch pan. Scatter pecans evenly over the caramel.
Mix filling: Combine brown sugar and cinnamon. Stir vanilla into the softened butter.
Punch down dough. Roll into a 12x16-inch rectangle on a floured surface.
Spread vanilla butter over dough, leaving a small border. Sprinkle with cinnamon sugar and press lightly.
Roll tightly from the long side and pinch the seam. Trim ends if needed.
Slice into 12 pieces. Arrange cut-sides up over the caramel and pecans.
Cover and let rise until puffy, 25–35 minutes. Preheat oven to 350°F near the end.
Bake 23–27 minutes until golden and set. Cool 5 minutes, then invert onto a platter and spoon over any extra caramel.