Preheat oven to 400°F + line a sheet pan with foil; thinly slice half mozzarella ball + set aside

Wipe 2 mushrooms with a damp paper towel, remove stems + using a spoon, scoop out the dark gills; place on sheet pan bottom-side up, season with salt/pep + drizzle with oil; bake 10 min then coat mushrooms in vinaigrette + add 1-2 slices of cheese onto each; bake 5-8 min more till cheese is melted

Toast 2 buns until warm + golden; wash + dry a few lettuce leaves

Divide mushrooms + lettuce to buns-Looks delicious!