To make the dough:

1. In a small bowl, combine 240 gm (1 cup) warm milk, yeast, and 1 teaspoon sugar. Let stand until the yeast is activated and foamy, about 10 minutes.
2. In the bowl of a stand mixer fitted with the paddle attachment, add 67 gm (1/3 cup) sugar, melted butter, sour cream, egg, and remaining 60 mL (1/4 cup) warm milk and mix on low speed until combined.
3. In a large bowl, combine 500 gm (4 cups) flour and the kosher salt. Add half of the flour/salt mixture to the sugar mixture and mix until just combined. Next, add in the foamy yeast mixture and mix on low speed until just combined. Then mix in the remaining flour/salt mixture until a shaggy dough forms, about 1 to 2 minutes.
4. Scrape down the sides and bottom of the bowl and switch to the dough hook attachment on your stand mixer. Knead on medium speed for 8 to 10 minutes, until the dough is smooth and elastic. Add up to the remaining 63 gm (1/2 cup) flour as needed, 1 tablespoon at a time, until the dough is pulling away from the sides of the bowl (TIP: Beat for 30 seconds after adding each additional tablespoon of flour to avoid adding too much). Continue to knead on medium speed until the dough is smooth, elastic, and passes the windowpane test*.
5. Turn the dough out onto a lightly floured surface and shape into a smooth ball. Place the dough in a lightly greased bowl, turning to grease the top of the dough. Loosely cover the bowl with plastic wrap and set in a warm, draft-free place until doubled in size, about 60 to 90 minutes.
6. Before your dough finishes the first proof, prepare the filling and set aside (instructions below). Grease a 9×13″ baking pan with non-stick spray and set aside for now.
7. Punch down the dough to remove all air and let it rest for 5 minutes. Turn the dough out onto a lightly floured surface and roll into an 18 x12″ rectangle. Spread the filling evenly over the dough, leaving a 1″ bare border along one long side.
8. Starting with the long side covered with filling, roll the rectangle into a tight jelly roll, pinching the dough together to form a seal. Using a sharp knife or unflavored dental floss, trim the ends of the dough and then divide into 12 equal rolls. Place the rolls in the prepared baking pan, being sure to space them out evenly to give them some room to grow. Loosely cover the pan with plastic wrap and leave to rise in a warm, draft-free place for another 30 to 45 minutes, until the rolls are puffy and beginning to crowd each other. In the meantime, preheat the oven to 350°F.
9. After the second rise, gently brush the warm heavy cream over each roll. Pour any remaining cream around the edges of the pan. Bake for 25 to 30 minutes, until lightly browned and an instant-read thermometer registers 190°F when inserted into the center of one of the rolls.
10. Let the rolls cool for 10 minutes before topping with cream cheese frosting (instructions below). Serve warm and enjoy!

To make the filling:

• In the bowl of a stand mixer fitted with the paddle attachment, add the softened butter, brown sugar, cinnamon and vanilla and beat on medium-high speed until combined and creamy.

To make the cream cheese frosting:

• Place the cream cheese and butter in the bowl of a stand mixer fitted with the paddle attachment and beat on medium speed until combined and creamy. Add the powdered sugar, vanilla and milk, and beat on medium-high speed until light and creamy, about 1 minute. Spread over warm rolls.