Place a rack in center of oven and preheat to 425 degrees.
Brush or rinse mushrooms clean and pat completely dry. Slice stems off even with the bottom of the cap and place mushrooms into a 9" x 13" baking dish with the stems facing up—the mushrooms will hold on to more of the garlic butter this way! Get in as many mushrooms as possible keeping them in a single layer. It's okay if they seem tight—they will shrink in the oven. Sprinkle top of mushrooms lightly with breadcrumbs and set aside.
Place a small skillet over medium heat and melt the butter. Once butter is melted, add garlic and cook for about 30 seconds just to remove raw taste from garlic.
Remove from heat and drizzle evenly over mushrooms then sprinkle lightly with salt.
Bake 18–20 minutes or until the tops begin to brown and get slightly crispy. Sprinkle with fresh chopped parsley and season to taste with a little additional salt and a few grinds of fresh pepper. Serve nice and hot as a side dish or appetizer with a little squeeze of lemon or with some crusty bread to soak up any extra garlic butter. Enjoy!
Notes
You can use any kind of breadcrumbs that you like: plain, fresh, dry—even gluten-free.