Position 1 rack in lower third of oven and 1 rack 3 inches from broiler; preheat to 425°F.
Toss 3 zucchini, 1 tablespoon oil, ½ teaspoon crushed red pepper and ¼ teaspoon salt in a large bowl until evenly coated. Arrange the zucchini in a single layer on a large rimmed baking sheet. Roast on the lower rack until tender-crisp, about 10 minutes. Remove from oven; increase oven temperature to broil. Return the zucchini to the top rack; broil until golden brown, about 5 minutes. Remove from oven. Lightly smash each zucchini round with the bottom of a small bowl.
Arrange the zucchini on a platter. Tear a 4-ounce burrata ball in half and place in the middle of the zucchini. Whisk 3 tablespoons pesto and 2 tablespoons lemon juice in a small bowl, adding water by the teaspoonful until a drizzling consistency is reached. Drizzle the pesto mixture over the zucchini. Garnish with basil leaves, if desired.
