- Heat olive oil in a 4-quart oven safe pan over medium-high heat. Add carrots, celery and onion. Sauté for 10 minutes to soften. Add garlic and ground beef, using a spatula to break up beef into crumbles. Continue to cook for 10 minutes longer, stirring occasionally.
- Stir in flour to coat beef and vegetables. Add wine and deglaze pan using a spatula to scrape up any browned bits of meat. Stir in beef stock, tomato paste and soy sauce. Bring to a boil. Stir in bay leaves, thyme, sea salt and black pepper. Reduce heat to medium low and simmer for 15-20 minutes uncovered until thickened, stirring occasionally. Discard bay leaves and stir in frozen peas. Remove from heat and cool mixture for 30 minutes.
- Preheat oven to 400ºF. Spread mashed potatoes evenly over meat and vegetable mixture without mixing the two. Bake for 20 minutes. Stir panko and melted butter together in a medium bowl to coat bread crumbs. Evenly scatter panko topping over mashed potatoes and return to oven for 10-15 minutes or until golden brown. Let shepherd’s pie stand at room temperature for 10 minutes before enjoying.