Preheat the oven to 350°F and lightly grease a 9-inch deep dish pie plate.
Place the quartered potatoes in a pot and cover them with salted water.
Bring to a boil, then reduce heat and simmer for about 20 minutes until the potatoes are tender.
Drain the potatoes and mash them with 2 tablespoons of butter and the minced garlic.
Season the mashed potatoes with salt and pepper, then set aside.
In a skillet, heat the olive oil over medium heat.
Add the ground beef, herbes de Provence, and nutmeg.
Cook and stir for about 10 minutes until the beef is browned and crumbly.
Spread the cooked beef evenly in the prepared pie plate.
Sprinkle the frozen peas evenly over the beef layer.
Spread the mashed potatoes over the peas to form the top layer.
Dot the top with the remaining butter.
Bake uncovered for about 20 minutes until the top turns golden and the pie is heated through.
