Begin by making the dough. Add the warm milk, instant yeast, sugar, eggs, and butter to the bowl of a stand mixer. Mix with a rubber spatula until everything is combined.
Add the flour and salt. Attach a dough hook onto the stand mixer and mix on low until a rough dough forms. Turn the mixer up to medium and let the dough mix for 5-6 minutes until a smooth dough forms. If the dough is really sticky, add a few more tablespoons of flour. The dough should be very soft and slightly sticky, but not really wet.
Cover the dough with a light towel or plastic wrap and set it aside to rise until it's doubled in size (about 1-1.5 hours).
When the dough is almost done rising, make the filling. Add the black sesame seeds to a coffee bean grinder or a food processor. Pulse until the sesame seeds are finely blended.
Add the butter, brown sugar, blended black sesame seeds, and cinnamon to a bowl. Stir until well combined and a paste forms.
When the dough is done rising, transfer the dough to a floured surface. Stretch and roll the dough out into a 12x18" rectangle. Add the paste onto the top of the dough. Use an offset spatula or rubber spatula to spread the filling evenly out on the dough, leaving about 1/2 inch uncovered on one of the long ends.
Starting on the opposite end of the uncovered strip, roll up the dough, sealing the ends so it doesn't unroll. Use a sharp knife to cut the log into 12 even cinnamon rolls, each one about 2 inches wide.
Transfer the rolls to a well-greased 9x13" pan. Cover with a towel or plastic wrap and let them rise for 30 minutes.
When the rolls are almost finished rising, preheat the oven to 350F. Transfer the rolls into the oven and bake for 20-25 minutes, until golden brown on top. Remove from the oven and let the rolls cool.
While the rolls are baking, make the frosting. Add the butter to a small pot over medium heat. Stir while the butter melts, then continue to stir while the butter starts to bubble and foam up. When the foam subsides, you'll be left with brown, nutty smelling butter.
Pour the brown butter into a bowl. Add the cream cheese and use a hand mixer (or stand mixer) to mix until combined. Blend the black sesame seeds. Add the powdered sugar, blended black sesame seeds, and vanilla extract. Mix again until a smooth frosting forms. Add the heavy cream and mix again.
Top each cinnamon roll with black sesame frosting and enjoy while they're warm!