Warm milk, heavy cream, and butter until a smidge warmer than lukewarm, about 100 degrees to 114 degrees (this can be done over the stove or in the microwave).*
Pour the mixture into the bowl of your standing mixer fitted with the paddle attachment.
Sprinkle the instant yeast and granulated sugar over the mixture. Allow to sit 5 minutes.
Then, add in eggs, vanilla extract, and salt. Mix until combined.
Remove the paddle attachment and attach the dough hook, and then add in 4 cups of flour and mix with the dough hook. Mix for about 5-7 minutes, until the dough has pulled away from the sides of the bowl, and is smooth and tacky, but not sticky. If the dough is still sticky, add in the remaining 1/2 cup of flour and continue to mix until it’s pulled away from the sides of the bowl and "tacky" feeling.
Then, turn out the dough onto a lightly floured surface and form into a ball (you can knead the dough a couple of times by hand, if desired).
Place cinnamon roll dough in an oiled bowl (I use baking spray to coat a glass bowl) and cover with a damp towel. Allow to rise in a warm place for about 45-60 minutes, or until it has about doubled in size.**