In a large bowl, whisk together 4 cups flour (520 grams), cake mix and yeast.
In the bowl of the stand mixer, add the milk and butter, making sure that the temperature is between 120-130ºF so that the yeast can activate.
Add the flour mixture to the milk/butter, then with the paddle attachment, mix until the ingredients are just combined.
Allow the mixture to sit for 10 minutes.
Switch to the dough hook and start the stand mixer on low speed to knead the dough. Add the remaining flour ¼ cup at a time, until a soft dough forms. You don't want the dough to be dry, so add the flour slowly. The dough should be slightly tacky to the touch.
Knead on low speed for 5-7 minutes.
Place the dough in a greased bowl, turning once to grease top. Cover and let rise until almost doubled, about 45 minutes.
While the dough is rising, mix together the filling: butter, sugars, flour and vanilla. Set aside.
Punch dough down. Turn onto a lightly floured surface; divide in half. Roll each portion into a 14x10-in. rectangle (you'll have 2 rectangles). Divide the filling mixture between the two rectangles and spread on top. Then add the sprinkles on top.
Roll up jelly-roll style, starting with a long side, making right roll. Cut each roll into 12 slices using a dough cutter or sharp knife (or floss makes a clean cut). place cut side down in two greased 13×9-in. baking pans. Cover and let rise until almost doubled, about 20 minutes.
Preheat the oven to 375ºF.
Pour ½ cup of warm cream over each of the risen pans of rolls.
Bake for 25-30 minutes or until golden brown. Check the rolls at 20 minutes. If they look like they are getting too brown, cover them loosely with foil for the remaining baking time.
For frosting, in a large bowl, cream the butter, confectioners' sugar and vanilla. Add milk, one tablespoon at a time, until you reach the spreading consistency you’d like. Add more milk if you’d like it to be a glaze rather than frosting.
Spread the frosting over the warm rolls. Sprinkle with additional sprinkles if you'd like.
Store in an airtight container at room temperature for 48 hours, then freeze or refrigerate any remaining rolls.
We often make the sweet rolls and get them to the point of the second rise (when they are rolled out, cut up and put in the pan). Cover and refrigerate until morning.The morning you want to bake them, pull them out of the refrigerator. They may have doubled in size in the fridge overnight. If they have, let them sit for 30 minutes to get the chill off, pour on the cream and then bake.If they did not rise in the fridge overnight, allow them to rise at room temperature. Plan about at least an hour for this. Then pour on the cream and let them bake.Refer to the article above for more tips and tricks.The calories shown are based on the recipe making 24 rolls, with 1 serving being 1 roll. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**