Place the warm milk in the stand mixer.
If it isn't warm, place into the microwave for 15-20 seconds.
Add the yeast to the mixer with the milk, mix into the milk and let sit for 5 minutes.
After the yeast has sat for 5 minutes, add the sugar, egg, egg yolk and the melted butter.
Mix everything together until combined.
Once everything is combined, add the flour and salt to the mixer.
Mix with a wooden spoon until a dough forms then add the dough hook to the stand mixer.
Knead the dough for 8 minutes with dough hook.
After the dough is done kneading, transfer to a well-oiled bowl and rest covered for for 1 1/2 hours in a warm spot.
After the dough has risen after 1 1/2 hours of resting, roll the dough out on a lightly floured surface into 14x9
Spread the filling over the entire surface as evenly as possible.
Roll up the dough into a log (14" side) as tight as you can.
Cut the log into 9 even pieces carefully with a sharp knife to prevent smashing the cinnamon buns.
Place the cinnamon buns into a well buttered casserole dish, cover the casserole dish and let rise for another 30-45 minutes.
Preheat the oven to 350 degrees.
After the second rise, add the half and half to the bottom of the casserole.
Place into the oven for 20-25 minutes.
While the cinnamon buns are in the oven, prepare the frosting.
Add the frosting ingredients to a small bowl and whip with an electric hand mixer until nice and fluffy.
Once the cinnamon buns are nice and golden brown, remove, top with the frosting and enjoy!