Spray a 9x13 pan with cooking spray.
In a small bowl combine the powdered sugar and heavy whipping cream. Pour into the pan. The mixture will be thick so you may have to use a spatula to spread evenly in the pan.
Sprinkle pecans and almonds over top of the milk/sugar mixture.
Place frozen cinnamon rolls on top of sugar/cream and nuts/
Cover with plastic wrap that has been sprayed with cooking spray [the part of the plastic wrap that touches the rolls].
Leave in fridge overnight. In the morning, let sit out covered at room temperature for 1 hour.
Bake at 350 degrees for 25-30 minutes.
After baking let cool on wire rack for 5 minutes.
Carefully take your pan and turn it upside down, over a serving platter or cutting board. Serve warm.