Preheat the Oven: Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper for easy cleanup (optional).

Prepare the Mushrooms: Gently remove the stems from the portobello mushrooms. Use a spoon to scrape out the dark gills from the underside of the caps (this prevents them from becoming soggy). Pat the mushrooms dry with a paper towel.

Season the Mushrooms: Brush the inside and outside of the mushroom caps with olive oil. Season with salt and pepper.

Mix the Filling: In a small bowl, combine the halved cherry tomatoes, fresh mozzarella, minced garlic (if using), and chopped basil. Toss gently to combine while prepping the fantastic stuffed portobello mushrooms.

Fill the Mushrooms: Spoon the Caprese filling into the mushroom caps, dividing it evenly among the four mushrooms.

Bake the Mushrooms: Place the stuffed mushrooms on the prepared baking sheet, and bake for 15-20 minutes, or until the mushrooms are tender and the cheese is melted and slightly golden. The edges of the mushrooms should be slightly golden brown, and the center will be slightly jiggly.

Drizzle with Balsamic Glaze: Remove the baking sheet from the oven and drizzle each stuffed portobello mushroom with balsamic glaze.

Serve and Enjoy: Serve immediately, while the mushrooms are warm and the cheese is melty. Garnish with extra fresh basil, if desired.