Add cream and milk to a small sauce pan and bring to a simmer, turn off heat and transfer to a stand mixer mixing bowl. Dissolve the sugar in the hot milk mixture using a whisk or spatula. Let it cool down to below 110°F.
Sprinkle active dry yeast over the liquid surface and let it bloom for 10 - 15 minutes, the mixture should puff up.
Add 2 cup of flour along with the salt to the liquid mixture. Knead with the dough hook on speed 2 until the dough comes together. If the dough is too wet, add the reserved flour, 1 tablespoon at at time, and continue kneading. The dough should still be wet but not too tacky.
Dump the dough out onto a lightly flour counter top and knead into a ball. Place the dough into an oiled bowl and let rise in a warm place for 2 - 3 hours until at least double in size.
Dump the risen dough out onto a lightly flour counter top, divide into 8 equal portions and shape into balls. Place dough balls on a lined baking sheet and let rest for 15 minutes.
Working with one dough ball at a time, press and stretch it out with your fingers into a circle about 3 - 4 inches in diameter. Add two tablespoons of red bean paste in the middle, and pinch the edges to seal the red bean paste inside. Place on a lined baking sheet seam side down.
Repeat with the rest of the dough balls and let rise in a warm place for 1 - 2 hours until double in size and puffy.
Preheat the oven to 400°F.
Beat one egg with a tablespoon of whole milk to make egg wash. Lightly brush egg wash all over the top and sides of the dough. Now dip the flat side of a small pestle into the egg wash, then immediately dip it into a bowl of sesame seeds, and lightly press the sesame seeds on top the dough.
Bake for 15 minutes until the top is golden brown. Rotate the pan during the last 2 - 3 minutes if necessary to brown evenly.