Heat 1 cup of whole milk and 4 tablespoons of unsalted butter over low heat until warm, about 110°F. In a mixing bowl, combine 2 ¼ teaspoons of instant yeast and ¼ cup of granulated sugar. Pour in the milk mixture, then add 1 large egg, 4 cups of all-purpose flour, and 1 teaspoon of salt. Using a stand mixer with a dough hook, mix on low speed for approximately 5 minutes until the dough is elastic and smooth.

Shape the dough into a ball and place it in a lightly greased bowl, covering it with a kitchen towel. Let the dough rise in a warm spot until it doubles in size, about 1 to 1.5 hours.

In a medium saucepan over medium heat, combine 2 cups of sliced rhubarb, ½ cup of granulated sugar, 2 tablespoons of lemon juice, and 2 tablespoons of cornstarch. Cook for about 10 minutes, until thickened to a jam-like consistency.

Preheat your oven to 350°F. After the dough has risen, punch it down gently. Roll it out into a rectangle, approximately 12x18 inches. Spread the cooled rhubarb filling evenly across the dough, then roll it up tightly from the long side. Cut into 12 equal pieces and place them in a greased 9x13 baking dish with the spiral side up.

Cover the cut rolls with a kitchen towel and let them rise again for 30 to 45 minutes.

Create an egg wash by whisking together 1 large egg with 1 tablespoon of water or milk. Brush this over the top of the rolls. Bake for 25 to 30 minutes, or until golden brown.

Mix 1 cup of powdered sugar with 2 tablespoons of reserved rhubarb filling and 1 tablespoon of lemon juice in a small bowl, whisk until smooth.

Allow the rolls to cool slightly for about 10 minutes, then drizzle the pink glaze over the warm rolls.