Root Vegetable Tian

Name: Root Vegetable Tian
Ingredients: 1 (15.5-ounce) can chickpeas, drained, 1/4 cup liquid reserved; 1 1/4 teaspoons kosher salt, divided; 2 small sweet potatoes, peeled and sliced crosswise into 1/8-inch-thick rounds; 3 medium-size red beets, peeled and sliced crosswise into 1/8-inch-thick rounds; 3 parsnips, peeled and sliced diagonally into 1/8-inch-thick slices; 2 small red onions, sliced crosswise into 1/8-inch-thick rounds; 2 ounces Parmigiano-Reggiano cheese, grated (about 1/2 cup); 2 teaspoons chopped fresh thyme; 2 tablespoons extra-virgin olive oil; 1/2 teaspoon black pepper; 3 garlic cloves, minced