Preheat oven to 400 degrees F.
Boil the potatoes in a medium-sized pot with 1 Tbs of salt until tender, about 20-25 minutes.
Drain and mash the potatoes then stir in the egg yolk.
While the potatoes are cooking prepare the meat. In a 12 inch oven-proof skillet, sauté the onion and carrots for 5 minutes. Add the ground meat, tomato paste, stock, salt, and spices to the skillet and cook for 10 minutes, stirring until the meat is crumbled.
Add the peas to the skillet and cook for the last 2 minutes.
Spread the mashed potatoes over the meat mixture. Decorate the peaks with a fork.
Bake the Shepherd's Pie in the oven for 30 minutes.
Serve and enjoy!