FOR THE POTATOES. Add the potatoes to a medium saucepan and fill with water until the potatoes are under 1 inch of water. Bring to a boil over medium-high heat. Boil 15 minutes or until fork tender. Drain water. Coarsely mash potatoes. Stir in cream cheese, garlic, and salt until well combined. Transfer to a bowl, cover, and set aside.
FOR THE FILLING. Preheat oven to 375°F. With a bit of neutral oil, brown the beef in a large saute pan with tall sides over medium-high heat. Drain excess fat. Stir in the onion, thyme, ground sage, salt, and pepper. Whisk the flour into the beef stock and stir into the beef. Cook for 10-15 minutes, stirring frequently, until liquid is almost entirely reduced. For the last 2 minutes, you may need to stir continuously to keep it from sticking to the pan. Remove from heat. Stir in the peas and carrots.
Divide beef mix between 2 24-oz ramekins or oven-safe bowls. Spread mashed potatoes over the top, leaving a ½-inch ring around the outer edge exposed. Bake for 25-30 minutes or until potatoes have begun to lightly brown on top and frozen vegetables are hot.
Serve warm to Mrs. Hall after she comes home from a long day out.
