Roast Chicken on Angel Hair Pasta

Name: Roast Chicken on Angel Hair Pasta
Ingredients: 1 pound angel hair pasta; 6 tablespoons olive oil , divided; 1 (15-ounce) can diced tomatoes with their juices; 1 teaspoon kosher salt , divided; 1/2 teaspoon freshly ground black pepper , divided; 1/4 teaspoon crushed red pepper; 2 tablespoons chopped fresh oregano , divided; 2 whole chicken legs (thighs and drumsticks attached), on the bone ( 1 1/2 pounds total); 2 large chicken breast halves, on the bone (1 1/2 pounds total); Fresh oregano leaves stripped from 1 sprig, for garnish