Preheat oven to 400 degrees. Cut about ¼-inch off top of garlic so most of the cloves are exposed. Place garlic in foil with 1 sprig of thyme and 1 Tbsp. oil. Seal foil to make packet and roast for 30 to 45 min. until golden brown and softened.
Meanwhile, brush foil-lined baking sheet with oil and lay sliced eggplant in single layer on sheet. In small bowl, mix Za’atar with 3 Tbsp. oil to make a paste. Brush each piece of eggplant with Za’atar paste. Place in oven until tender and just browned, about 8 to 10 min.
Bring pizza dough to room temperature and roll out on floured surface to create rectangular shape. Place dough on parchment-lined baking sheet, brush with oil and poke a few holes in dough using a fork. Bake dough for 15 min. until lightly browned.
When garlic is cool enough to handle, remove cloves by squeezing them out of their skins.
Remove dough from oven and brush top and edges lightly with remaining Za’atar paste. Spread ricotta cheese onto dough and top with eggplant, roasted garlic cloves, mozzarella and leaves of remaining thyme sprigs. Sprinkle with garlic salt, and bake for 15 min. or until lightly browned.
Top cooked pizza with arugula.
Serve as an appetizer or main course.