Preheat your oven to 375°F.
In a skillet, heat the olive oil over medium heat. Add the minced garlic and sauté until fragrant, about 30 seconds.
Add the lean ground beef to the skillet, season with a pinch of salt and pepper, and cook until browned, breaking it up into small pieces.
Stir in the mixed vegetables and cook for an additional 3-4 minutes until they begin to soften. Remove from heat.
Meanwhile, peel (if desired) and boil the red potato until tender, about 10-12 minutes. Drain well and mash with the skim milk, adding a dash of salt and pepper to taste.
Transfer the cooked ground beef and vegetable mixture into a baking dish, spreading evenly.
Top the mixture with the creamy mashed potato, using a spatula to create an even layer.
Bake in the preheated oven for 15-20 minutes, or until the top starts to turn lightly golden.
Let cool for a few minutes before serving.