Day 1: Dissolve sugar in the water, add starter and whisk together, add flour, mix well, form a ball, place in jar, cover let ferment at room temp 74-78F until it increases in volume in 2 or more times.

Day 2: In a bowl of stand mixer add milk, heavy cream, an egg, sugar, stiff sourdough starter (60 g), yeast (if using) and the flour, mix all together let autolyse for 30 min.

Mix dough on low speed of your mixing machine for 2-3 minutes, or KitchenAid on speed 3 for 3-4 minutes until well incorporated.

Add salt mix for a couple more minutes. The dough should form a ball.

Add soft cream cheese and soft butter, increase the speed of mixer, mix for 10 more minutes until the dough is well incorporated and comes up together.

Cover the dough and let it proof for 3-4 hours at 76-80F.

Transfer the dough to the fridge for cold fermentation for about 6-9 hours.

Remove the dough from the fridge. Divide on 9 equal pieces (about 55g each). Pinch all edges to the bottom of a roll, try to round it tightly.

Transfer the shaped rolls into the square baking pan. Cover rolls and let them proof overnight for 8 -10 hours.

Preheat the oven to 335F. Sprinkle some flour on top of the buns or egg wash them.

Bake for 8 minutes, then place the tray on the top rack of your oven, to block the heat from the top. Cover buns with foil to prevent browning.

Let buns to bake for 15-17 more minutes (total baking time 23-25 min).