Preheat the Oven: Start by preheating your oven to 350°F. Lightly grease a 9x13-inch baking dish.
Prepare the Chicken Mixture: In a large bowl, combine the shredded rotisserie chicken, cream of chicken soup, thawed mixed vegetables, 1 cup of shredded cheese, seasoning salt, garlic powder, onion powder and heavy cream. Mix until everything is well combined.
Cut the Biscuits: Open the can of refrigerated biscuits and cut each biscuit into quarters.
Add to Baking Dish: Transfer the chicken mixture into the prepared baking dish. Spread it out evenly. Sprinkle the remaining one cup of the shredded Colby Jack cheese evenly over this layer.
Top with Biscuits: Lightly place the biscuits on top of the casserole without overlapping and pushing them into the chicken mixture too far, this ensures that the bottoms of the biscuits will cook and not get too soggy.
Bake the Dish: Brush the melted butter evenly over the top of the biscuits. Place the baking dish in the preheated oven and bake for about 35-40 minutes, or until the biscuits are golden brown and the casserole is bubbly. (Check at the 20-25 minute mark, if biscuits are cooked and browned to your liking cover dish loosely with foil and continue cooking for the remainder of the time so the biscuits do not burn)
Serve: Let the bubble up bake cool for a few minutes before serving because it will be piping hot right out of the oven.