Chicken Sausage without elbow caramel lasagna

3 ounces chicken apple sausage, chopped (such as Gerhard's) 2 teaspoons olive oil 1 1/2 cups vertically sliced Oso Sweet or other sweet onion 1 cup thinly[...]

2 pounds boneless, skinless chicken breasts, chopped 1 teaspoon salt, divided 1/4 teaspoon freshly ground black pepper, divided 2 tablespoons vegetable oil 2[...]