1. Fill a medium pot with water, add a generous pinch of salt, and bring to a boil over medium-high heat.

2. Add the potato pieces and boil for 7-8 minutes or until fork-tender.

3. While potatoes are cooking, combine butter and milk in a small saucepan. Heat over medium heat, whisking occasionally, until butter is completely melted. Alternatively, microwave in 30-second intervals, whisking between each, until butter melts.

4. Drain the cooked potatoes thoroughly and return them to the pot.

5. Mash the potatoes to your desired consistency using a potato masher or fork.

6. Gradually stir in the warm butter-milk mixture until fully incorporated.

7. Season with garlic powder, salt, and pepper. Stir well and adjust seasonings to taste. Set aside.

8. In a small bowl, whisk together cornstarch and 1/4 cup of the beef broth until smooth. Set aside.

9. Heat a large skillet over medium heat. Add ground beef and cook, breaking it into small pieces, until no longer pink.

10. Drain excess fat from the skillet.

11. Add the remaining 1 3/4 cups beef broth, chopped onion, garlic powder, salt, and pepper to the skillet. Stir to combine.

12. Simmer uncovered for 5-10 minutes until the onion is tender.

13. Slowly pour the cornstarch mixture into the skillet while gently whisking. Increase heat and bring to a boil.

14. Cook for 2 minutes, stirring constantly, until the gravy has thickened.

15. Divide the mashed potatoes among serving bowls.

16. Top each portion with ground beef and gravy.

17. Serve hot, with extra gravy if desired.