Chef’s Note: I apologize for the lack of step-by-step photos. I was making this for about 25 ladies at a Sunday brunch. I did manage to shoot a final image, and a few other images, but that was about it.
Place a rack in the middle position, and preheat the oven to 370 (190c).
Place 1 tablespoon of grapeseed oil into a skillet, over medium heat.
When the pan comes up to temperature, place the Portobello mushroom in the pan, and cook for about 1 minute per side.
Chef's Tip: This searing of the Portobello will give it more of a "meaty" taste.
Remove the Portobello, and reserve.
Add the second tablespoon of grapeseed oil, and the butter to the pan, and reduce the heat to medium.
Add the chopped white button mushrooms, and cook until softened and beginning to brown.
Remove from the pan, and reserve.
Place the provolone cheese in the Portobello mushroom.
Add the sautéed white button mushrooms.
Add the tomato sauce.
Add the colby/jack cheese, and the Parmesan.
Bake in the preheated oven until the cheese is bubbly, and beginning to brown in spots, about 20 minutes.
Sprinkle a bit more Parmesan on top (optional), and serve while still nice and toasty. Enjoy.