Heat your oven to 350°F.

In a large frying pan over medium-high heat, heat half of the olive oil. Once hot, add half of the mushrooms and let them brown for 1 to 2 minutes without moving them.

Add ½ teaspoon kosher salt, black pepper, and half the garlic, then stir to brown the mushrooms on more sides until they release their liquid.

Cook the mushrooms until most of the liquid cooks off, leaving a thin puddle. Scrape into a large bowl and repeat with the remaining olive oil, mushrooms, and garlic.

Combine the cooked mushrooms in the bowl, add diced cream cheese, and stir until combined.

Add half of the panko, all of the gruyere, half of the parmesan, and most of the parsley, stirring to combine.

Transfer the mixture to a 2-quart baking dish.

Combine the melted butter with the remaining panko and parmesan, sprinkle over the top of the mushrooms.

Bake until the breadcrumbs are light golden brown, about 25 to 30 minutes.

Sprinkle with remaining parsley and serve immediately.