• In a large saucepan, heat the milk (360ml), butter (85g), and sugar (70g) until the butter has melted and the sugar has dissolved.
• Remove from the stove, pour it into your mixing bowl and set a side to cool to about 100°F.
• To the milk mixture add 2 cups of flour (240g), egg (1), egg yolk (1), yeast (2 1/4 teaspoons), and salt (3/4 teaspoons).
• With the dough hook attachment on and on low speed sprinkle the rest of the flour (390g). Knead until you have a smooth dough with no dry flour.
I found that adding 3 cups (360 vs. 390g) of flour is enough, so I recommend starting with the smaller amount then adding the rest 1/4 cup (30g) if needed.
The dough might feel sticky, that's ok do not be tempted to add more flour.
• Transfer the dough to a large bowl (or leave it in the mixing bowl), cover with plastic wrap and set at a warm spot in your kitchen until double in size, about 75-90 minutes.
• While the dough rests, make the filling: measure the light brown sugar (300g), butter (170g), potato starch (1 tablespoon) and cinnamon (2 teaspoons). Use a hand mixer to cream until you have a smooth mixture.

Assemble the rolls

• Line a 9x13-inch pan with parchment paper.
• Use your hands to deflate the dough, then place it on a clean surface lightly sprinkled with flour. Use a rolling pin to roll the dough to a 16x18-inch rectangle.
• Using an offset spatula, spread the filling over the surface of the dough.
• Tightly roll the dough into a log starting from the 18-inch end.
• Use a serrated knife to cut the dough into 12, 1.5-inch slices. Place each slice over the prepared pan swirl side up.
• Cover the rolls with a kitchen towel and set aside to rest for another 60-75 minutes.
• Preheat your oven to 350°F about 20 minutes before baking.
• Brush the rolls with the heavy cream and pour what is left between the gaps of the rolls.
• Bake the rolls over the oven's middle rack for 25-30 minutes. Until the rolls are medium golden and the inner temperature of the middle roll is 180°F.
• While the rolls are baking make the frosting by mixing the ingredients in a medium-sized bowl.
• Once out of the oven drizzle with the frosting and serve.
• The rolls are best the same day and should be stored at room temperature, covered for up to three days.

  To reheat: place the rolls over a pan lined with parchment paper and bake for 10-15 minutes in a 300°F pre-heated oven.