Heat the milk until it just reaches a simmer, then remove from heat and let cool until warm to the touch. Stir in 1 tablespoon of the sugar, sprinkle the yeast over the milk, and let sit until foamy.
In the bowl of a stand mixer fitted with a dough hook attachment, add the milk mixture, remaining sugar, sour cream, butter, and egg. Mix briefly to combine.
Add the flour and salt. Mix on low speed for 2 to 3 minutes until combined, then increase to medium speed and mix for another 2 to 3 minutes. The dough will be very soft and sticky.
Transfer the dough to a lightly oiled bowl using wet hands. Cover and let rise in a warm place for about 1 hour, until puffy and expanded.
While the dough rises, mix the sticky schmeer ingredients until smooth and spreadable.
Line a baking pan with parchment paper and lightly spray with pan spray.
Turn the dough out onto a generously floured surface. Gently fold once or twice to coat the outside, then use a rolling pin to roll into an 18-by-12-inch rectangle.
Spread the sticky schmeer evenly over the dough, leaving a 1-inch border along one long edge. Roll tightly into a log and slice into twelve 1½-inch rolls.
Arrange the rolls in the prepared pan. Cover and let rise for 30 to 45 minutes, until puffy and just touching.
Preheat the oven to 350°F. Spoon heavy cream over the tops of the rolls, letting it run down the sides.
Bake for 30 to 35 minutes, until lightly golden and the centers reach 180 to 190°F.
Whisk together glaze ingredients until smooth. Pour over the rolls while they are still warm.