Prep Station → Slice mushrooms paper-thin, shred cheese, mince garlic, strip thyme—set toaster or oven to broil.

Dry Sauté → Heat large skillet over high; add mushrooms in one layer—no oil yet—cook 3 minutes until liquid evaporates.

Golden Mushrooms → Drizzle olive oil; stir in shallot and garlic—sauté 2 minutes until edges crisp and fragrant.

Herb Magic → Sprinkle thyme, season with salt/pepper—toss 30 seconds; remove from heat.

Toast Base → Place sourdough slices on baking sheet; toast under broiler 1 minute per side until golden.

Mushroom Pile → Divide warm mushroom mixture evenly atop each toast—press gently to adhere.

Cheese Blanket → Sprinkle half the Swiss under mushrooms, half on top—maximum melt insurance.

Final Broil → Return to broiler 1-2 minutes—watch closely until cheese bubbles and browns.

Bright Finish → Drizzle balsamic glaze in thin ribbons; add pepper and optional arugula.

Serve Immediately → Plate with knife and fork—enjoy the melty, earthy perfection while hot.