For the dough: In a small bowl, combine warm milk, sugar, and yeast. Let it sit for 5-10 minutes until foamy.

In a large bowl, whisk together flour and salt. Add the yeast mixture and melted butter. Mix until a shaggy dough forms.

Turn the dough out onto a lightly floured surface and knead for 8-10 minutes until smooth and elastic. Place in a greased bowl, cover, and let rise in a warm place for 1 hour, or until doubled in size.

For the filling: In a medium bowl, combine chopped rhubarb, sugar, cornstarch, cinnamon, nutmeg, and lemon juice. Mix well.

Punch down the risen dough and roll it out into a large rectangle (about 12x18 inches) on a lightly floured surface.

Spread the rhubarb filling evenly over the dough, leaving a small border around the edges.

Roll up the dough tightly, starting from one of the long sides. Slice the roll into 12 equal pieces.

Place the rolls cut-side up in a greased 9x13 inch baking dish. Cover and let rise for another 30 minutes.

Preheat oven to 375°F (190°C). Bake the rolls for 20-25 minutes, or until golden brown and the filling is bubbly.

For the glaze: Whisk together powdered sugar, milk, and vanilla extract until smooth. Drizzle over warm rolls.