Preheat your oven's broiler to High (or set your oven to bake at 425°F / 220°C). Arrange the thick slices of artisan bread in a single layer across a large baking sheet. Brush both sides of each slice lightly with extra virgin olive oil.
Place the baking sheet under the broiler for 2 to 3 minutes, watching carefully, until the edges of the bread turn beautifully golden and crisp. Remove from the oven.
Immediately rub the cut side of your raw garlic clove firmly across the top surface of each hot, toasted bread slice to infuse it with aroma.
Layer a generous, even amount of mozzarella cheese onto each garlic-rubbed toast base. Arrange 2 to 3 slices of tomato directly over the cheese layer. Season the tops evenly with flaky sea salt and cracked black pepper.
Return the baking sheet to the oven under the broiler. Cook for 3 to 5 minutes until the mozzarella cheese is completely melted, bubbling with golden spots, and the tomato rounds look beautifully wrinkled and roasted.
Remove from the oven and transfer the hot toasts to a wooden serving board. Scatter the freshly chopped basil leaves over the bubbling cheese. Drizzle with an optional splash of sweet balsamic glaze or extra virgin olive oil if desired, and serve immediately.