1.Cut zucchini and summer squash lengthwise ¼ inches thick. Brush with 1 tablespoon olive oil, season with salt and pepper, and grill over medium-high until charred and just tender, 3 minutes per side. Toss scallions with 1 teaspoon olive oil and grill, turning occasionally, until just tender; transfer to a board and cut into pieces.
2.Split ciabatta bread and grill until toasted, 1 minute per side, then rub each cut side with 1 large clove garlic and brush with 1 tablespoon olive oil.
3.Spread ricotta on each half, then top with zucchini, squash, and scallions. Zest lemon on top and drizzle with 1 tablespoon olive oil.