Step 1

Preheat oven to 375°F. Combine chickpeas, reserved 1/4 cup chickpea liquid, and 1/4 teaspoon salt in a food processor; process until mixture is mostly smooth, about 30 seconds. Spread puree evenly on bottom of a 9-inch round (2-quart) baking dish. Starting at outer edge of dish, arrange groupings of 2 or 3 slices of each vegetable, layering and overlapping slightly, in 2 concentric circles, using chickpea puree to steady slices. Tuck remaining vegetable slices in center to fill up dish.

Step 2

Stir together cheese and thyme in a small bowl. Brush top of vegetables with oil; sprinkle with pepper and remaining 1 teaspoon salt. Scatter cheese mixture and garlic over tian.

Step 3

Cover tightly with aluminum foil, place on a baking sheet, and roast in preheated oven 35 minutes. Uncover and roast until top is lightly browned and vegetables are tender when pierced with the tip of a paring knife, 25 to 30 minutes. Serve warm or at room temperature.