Mix and knead (stand mixer): Bowl: add flour, yeast, sugar, salt. Stir to combine.
Add warm heavy cream + egg. Mix on low until shaggy, 1–2 min.
Add melted butter. Knead with dough hook on low–medium until smooth and elastic, 6–8 min.
Dough target: soft, smooth, slightly tacky. If stiff/dry: add 5 g (1 tsp) warm water at a time. If very sticky/soupy: add 8–10 g (1 tbsp) flour at a time.
Rest: Cover and rest 10 minutes.
Roll and fill: 1. Roll to about 35×25 cm (14×10 in) rectangle. 2. Spread 56 g soft butter. 3. Mix brown sugar + cinnamon (+ pinch salt) and sprinkle evenly. 4. Roll tightly from the long side into a log. 5. Cut into 9–12 rolls and place in a buttered 9×13 pan.
Proof: Cover and proof 25–45 min until puffy and mostly touching.
Bake: Preheat 350°F (175°C). Optional: pour 120 g (½ cup) heavy cream around rolls right before baking. Bake 18–24 min until golden and set (center rolls ~190°F / 88°C if you temp).
Ice: Cool 5–10 minutes (warm, not hot).
Make the icing: 1. Beat cream cheese + butter until perfectly smooth. 2. Beat in powdered sugar + vanilla + pinch of salt. 3. Add 15 g (1 tbsp) cream at a time until spreadable.