1. 1. Preheat the oven to 375°F (190°C).

2. 2. In a large bowl, mix together the ranch dressing mix and 1 cup of 1% milk until well combined.

3. 3. In a separate bowl, toss the chicken drumsticks with all-purpose flour until coated.

4. 4. In a large baking dish, layer the diced onions, diced tomatoes, and egg noodles.

5. 5. Place the chicken drumsticks on top of the noodle mixture.

6. 6. Arrange the russet potatoes around the chicken pieces.

7. 7. Pour the ranch dressing mixture over the casserole, making sure everything is evenly coated.

8. 8. Cover the baking dish with foil and bake for 45 minutes.

9. 9. Remove the foil and bake for an additional 15 minutes or until the chicken is cooked through and the potatoes are tender.

10. 10. Serve hot and enjoy!