2 medium yellow onions, quartered and sliced
2 garlic cloves, minced
1/4 cup butter
1 pound refrigerated pizza dough, at room temperature
2 tablespoons chopped fresh herbs (combination thyme, rosemary and oregano leaves)
1/4 cup grated Cheddar
1/4 cup grated Parmesan or Pecorino
Salt and freshly ground black pepper
1/2 cup balsamic vinegar
1/4 cup extra-virgin olive oil
1 tablespoon red pepper flakes