1-First, preheat your oven to 400 degrees Fahrenheit to get everything ready for baking. In a small bowl, combine 1 tablespoon of olive oil with the minced garlic and set it aside for that flavorful base. Then, heat the remaining tablespoon of olive oil in a skillet over medium-high heat and sauté the onions and mushrooms for 3 to 5 minutes until they soften up nicely.

2-Next, place the flatbreads on a baking sheet and brush them with the garlic olive oil mixture for extra taste. Top with the shredded Fontina cheese, mushrooms, and onions, then season with salt and pepper to bring out the flavors. Bake for about 12 minutes, or until the cheese melts and everything looks golden.

3-While the flatbreads bake, prepare the crispy sage leaves by heating about 1/4 cup olive oil in a small skillet and frying the sage leaves for 5 to 10 seconds until they crisp up. Drain them on paper towels and add them to the baked flatbreads. For dietary adaptations, use vegan butter or oil substitutes in the sauté step. Once done, cut the flatbread into pieces and serve it warm for the best experience.