Preheat oven to 375*F
In a large skillet, melt butter over medium heat.
Add brown sugar and stir until incorporated.
Add cinnamon and nutmeg, mix well.
Add diced apples and stir to coat. Simmer mixture for 5 minutes or until apples are soft and to the desired texture. I recommend tasting one to see if it's soft enough.
In a small bowl combine cornstarch and water. Mix well then add cornstarch mixture to apples and stir. Remove from heat and set aside.
In a 9x13 casserole dish, lay out croissant pieces, spreading out so they cover the bottom of the pan.
Top croissants with apple mixture. Spreading evenly over croissants.
In a separate bowl combine heavy cream, apple butter (or apple sauce), eggs and cinnamon. Mix well.
Pour apple butter mixture over croissants and apples. Drizzle over the top to cover apples.
Bake for 25 minutes.
When casserole is removed from oven, allow to sit for 5 minutes.
While casserole is cooking, in a small bowl combine heavy whipping cream and powdered sugar ¼ cup at a time. Add more heavy cream ½ teaspoon at a time if needed. Mixture should be thick but should drip from spoon when held in air.
Drizzle casserole with icing and serve immediately.
