Place melted butter in a 9-inch pie plate and tip to coat the bottom and sides. Preheat the oven to 350 degrees.
Scatter cinnamon roll pieces evenly in the pie plate.
In a bowl, toss apples with the brown sugar and cinnamon. Scatter on top of the cinnamon roll pieces.
In a small bowl, whisk together eggs, heavy cream, and vanilla. Pour over the cinnamon rolls and apples.
Bake for 18 to 20 minutes.
Spread the icing that came with the cinnamon rolls on top and serve warm.
Notes
Any kind of apple can be used. I like Granny Smith, Gala, or Honeycrisp.Cut the apple into small pieces. The casserole doesn't bake for long and you want the apple pieces to get soft and not be crunchy.