Wash and dry all produce. Adjust rack to upper position and preheat oven to 450 degrees. Trim and discard bottom inch from baby broccoli, then chop stalks and florets into bite-size pieces. Halve zucchini lengthwise, then slice into thin half-moons. Mince garlic.

Heat a large drizzle of olive oil in a large pan over medium-high heat. Add zucchini and baby broccoli. Cook, tossing, until tender and starting to brown, 5-7 minutes. Season with salt and pepper. Toss in garlic and cook until fragrant, about 30 seconds.

Thinly slice mozzarella or tear it into small pieces with your hands. Finely chop sun-dried tomatoes.

Place flatbreads on a lightly oiled baking sheet. Spread pesto over top of each. Scatter mozzarella, baby broccoli, zucchini, and sun-dried tomatoes in an even layer on top.

Bake flatbreads in oven until cheese is melted and crust is starting to brown, 5-7 minutes.

Cut baked flatbreads into slices and serve.