caramelized onion blue cheese biscuits with roasted tomatoes - Pass the Cookies

Ingredients

• 3 cups flour
• 4 ½ teaspoons baking powder
• 2 tablespoons sugar
• ¾ teaspoon cream of tartar
• ½ teaspoon sea salt
• ¾ cup unsalted butter, cold and cut into cubes
• ¾ cup blue cheese crumbles
• ½ cup caramelized onion (from about 2/3 onion), cooled
• ¼ teaspoon freshly ground pepper
• 1 large egg
• 1 cup + 1 tablespoon whole milk
• 1 large egg, whisked
• 2 tablespoons olive oil
• 1 tablespoon unsalted butter
• 2 large onions, sliced
• 1 tablespoon balsamic vinegar
• 2 pounds cherry tomatoes
• ¼ cup coarsely chopped basil
• ¼ teaspoon red pepper flakes
• Salt and freshly ground black pepper, to taste