Preheat oven to 475°F. Coat 17- x 12-inch baking sheet with 2 tsp. oil or line with parchment paper. Press doughs together to form ball. Spread and press dough to 1/4-inch thickness on prepared baking sheet, leaving dough in free-form shape. Mix garlic and 2 tsp. oil in bowl. Brush garlic mixture over dough, leaving 1/2-inch border.Crumble goat cheese over dough, then sprinkle with fontina cheese. Arrange zucchini, tomatoes, and yellow squash over pizza. Brush with remaining 1 Tbs. oil.Scatter onion and bell pepper over vegetables. Sprinkle with red pepper flakes, if desired, and season with salt and pepper. Bake 30 minutes, or until puffed and deep brown at edges. Cool 10 minutes, then cut into squares.