French-Style Cottage Pie (Hachis Parmentier)

Steps

1. About 30 minutes before cooking, remove the beef from the fridge, sprinkle with 1/2 tsp salt, and let it come to room temperature.
2. Heat oil and butter in a large skillet over medium heat. Add garlic and cook 2 minutes until fragrant.
3. Add onions and carrot; cook about 5 minutes until softened and fragrant.
4. Increase heat to medium-high. Add ground beef, remaining 1/2 tsp salt, pepper, and nutmeg. Break up the meat and cook 6-7 minutes until browned and most moisture has evaporated.
5. Add beef stock and cook another 7-8 minutes until most liquid has evaporated.
6. Remove from heat. Stir in egg yolk and parsley. Adjust seasoning to taste. Set aside to cool.
7. Place potatoes in a large pot, cover with water by 2 inches, and add 1 tbsp salt. Bring to a boil and cook about 15 minutes until fork-tender.
8. Preheat oven to 350°F (180°C).
9. Drain potatoes and let steam off for 5 minutes. Transfer to a bowl, add milk, and mash to desired texture. Fold in butter and adjust seasoning.
10. Spread the cooled meat filling in the bottom of a 11.5" x 8.5" (29cm x 22cm) baking dish.
11. Spoon mashed potatoes over the meat and spread evenly. Score the top with a fork and sprinkle with breadcrumbs.
12. Bake for about 30 minutes until golden and bubbling. Let cool 15 minutes before serving.