Remove the mushroom stems and, using a small spoon or grapefruit knife, core the mushrooms to create a deep well for the cheese filling. Place the cored mushroom caps top down in an oven safe, non-stick casserole dish.

In a medium-sized bowl, mix the whipped cream cheese, ½ cup of the Parmesan cheese, ½ cup of the white Cheddar, minced garlic cloves, and Ranch seasoning. Tamp the cheese mixture into the mushroom caps to completely fill the cap. Do not overstuff, however, to prevent the cheese from oozing over when the mushrooms get baked.

In a small mixing bowl, add the Panko crumbs, ½ cup Parmesan cheese, minced Italian parsley, garlic salt, and 2 TBL of the butter (melted). Mix well until all the breadcrumbs are well coated in the melted butter. Spoon the Parmesan crumb topping over each of the stuffed mushroom caps.

Bake the mushrooms in a preheated 375F oven, on the center rack, for 20 minutes.

While the mushrooms are in the oven, make the Four-Cheese sauce. In a small saucepan, melt ¼ stick unsalted butter. Whisk in the whole milk and bring to a slight simmer. Add the Provolone, Mozzarella, and remaining Parmesan and Cheddar. Whisk until all the cheese has melted. Add the white pepper, a pinch of kosher salt, and 2-3 cranks of cracked black pepper. Simmer the sauce for about 5 minutes, whisking very frequently, until the sauce has thickened.

Once the mushrooms have been removed from the oven, using a 2-ounce ladle, ladle the four-cheese sauce between the stuffed mushroom caps. Serve immediately and enjoy!