Add milk to a heatproof bowl and microwave for 20-30 seconds, until warm. Add the milk, instant dry yeast and granulated sugar to the bowl of a stand mixer fitted with a dough hook. Stir on low to incorporate.

Add in the melted butter, vanilla extract and eggs and mix on low until combined. While the mixer is on low, add the flour one cup at a time and then the salt. Mix on low for an additional 5 minutes. This will knead the dough so you don't have to! If you do not have a stand mixer, knead by hand. When the 5 minutes is up, fold in the sprinkles until just incorporated. Add the dough to a well oiled (with vegetable oil or butter) large bowl. Cover loosely with a towel or plastic wrap and place in the oven (not turned on) to let it rise for 1 hour. After 1 hour, the dough should almost double in size.

While the dough is rising, make your filling! In a small bowl combine the softened butter, brown sugar, cinnamon, vanilla and salt. Set aside until needed.

Grease and line a 9x13 inch baking pan with parchment paper and set aside, When the dough has risen, punch down the dough and empty out onto a counter lightly dusted with flour. Roll into a 20×14 inch rectangle. Spread softened butter mixture over dough, leaving a ¼ inch margin at the far side of the dough.

Starting with the longest edge closest to you roll the dough into a log, keeping it tight as you go. Use a sharp serrated knife and cut into 12 even rolls. Place the cinnamon rolls into the prepared baking pan. Cover with plastic wrap and let rolls rest for 30-45 minutes at room temperature to allow them to rise. If you'd like to make these the next day, cover with plastic wrap and place in the refrigerator overnight. (see below for notes on how to make these overnight)

Preheat the oven to 350°. Remove the clear wrap and pour ¼ cup heavy cream between the rolls. Bake for 20-25 minutes, or until they start to turn golden brown. You want to slightly underbake them so they stay soft!

Mix together the soft butter, vanilla and salt. Add powdered sugar and beat until smooth. Depending on how thin you want your frosting, add 1 tablespoon of heavy cream or milk at a time until it reaches desired consistency. Spread the frosting on the rolls and top with extra sprinkles. Enjoy!