Preheat the oven to 375 degrees F (190 degrees C).
Rub a medium baking dish with a little olive oil and set aside. You could also use a cast iron skillet if you like!
Combine the Short Grain Brown Rice (1 1/4 cup) and Mushroom Broth (2 1/4 cup) in a medium pot and bring to a boil. Lower to a simmer, cover, and cook for 45 minutes until the liquid has been absorbed.
Remove from the heat and let rest for 5-10 minutes, covered, then fluff with a fork.
Place the Bacon (6 slice) on a rack over a foil lined baking sheet. Bake for 25 minutes until brown and crispy. When cool enough to handle, crumble the bacon and set aside until ready to use.
Meanwhile, prep other ingredients. Slice the Leek (2), Shiitake Mushroom (1 1/2 cup), and Cremini Mushroom (1 1/2 cup).
Mince the Yellow Onion (1/2) and Garlic (4 clove). Chop the Fresh Thyme (2 teaspoon) and Sage Leaves (6).
Rinse and drain the Canned Cannellini White Kidney Beans (19 ounce).
Grate the Gruyère Cheese (1 cup), Fontina Cheese (3/4 cup) and Parmesan Cheese (1/4 cup).
Heat the Olive Oil (1 1/2 tablespoon) in a large sauté pan over medium heat. When hot, add the leeks, onions and garlic and cook until soft, about 5 minutes.
Add the mushrooms, thyme, and sage and cook for 8 minutes until the mushrooms have released their liquid and are tender.
Add the beans and cook for 1 minute until heated through.
Stir in the cooked brown rice and turn off the heat.
Add 2/3 of the crumbled bacon and 2/3 of the Fontina and 2/3 of the Gruyere and mix until well combined. Taste and season with a healthy amount of Freshly Ground Black Pepper (to taste) and Kosher Salt (to taste), if needed.
Turn out the rice mixture into the prepared baking dish and top with the remaining fontina and gruyère.
In a small bowl, combine the Whole Wheat Panko Breadcrumbs (1/4 cup) and Parmesan Cheese. Sprinkle the mixture in an even layer over the casserole.
Transfer the casserole to the oven and bake for 25 minutes until the cheese is bubbling and the top is lightly browned.
Garnish the casserole with the remaining crumbled bacon and Fresh Parsley (2 tablespoon) and serve hot.