First, dissolved the yeast in a bowl with the warm milks and a teaspoon of sugar. Let the mixture bloom for 10 minutes and set aside.
Next, add the sugar, butter, salt, eggs, and flour to the bowl of your stand mixer and mix until well combined. Then add your yeast mixture and mix until your dough forms and it pulls away from the side of your bowl.
Put your dough in bowl that has been coated with oil and cover it with plastic wrap. Place your bowl in a warm spot and let rest for at least an hour.
Prepare your 9x13 baking pan by spraying it with cooking spray.
Once your dough is done rising, start rolling it out on a lightly floured surface. Your rectangle should be approximately 15x12 inches and 1/4 inch thick.
In a bowl, combine your brown sugar and cinnamon together.
Smear your butter over the dough followed by your cinnamon mixture making sure the dough is evenly covered.
Starting from the long side of the rectangle, carefully roll your dough until you reach the other side and have one large log.
Cut the log into 12 cinnamon rolls using a knife or dental floss. Place the cinnamon rolls on your prepared baking pan and cover with plastic wrap. Place your pan in a warm spot and let them rest for 30 minutes.
Preheat your over to 350°F. Place you baking pan in the oven and bake for 20 minutes or until your cinnamon buns are lightly golden brown.
For the frosting, beat the butter until it is fluffy.
Slowly add in the powdered sugar making sure to scrape down the sides of the bowl so everything is incorporated.
Add the vanilla and milk until you reach your desired consistency.
Once your buns are done baking, allow them to cool for 10 minutes before spreading the frosting overtop and serving.