• Follow this blog post to make the mashed potatoes. Cook using the desired cooking method, then set aside.
• In a large skillet over medium heat, warm the olive oil. Add the diced onion and sprinkle with 1/2 teaspoon of salt. Sauté for 6-8 minutes, or until the onions soften and begin to brown. 
• Once the onions are beginning to brown, stir in the garlic, tomato paste, and thyme. Sauté for another 1-2 minutes, stirring frequently to prevent burning. 
• To the same skillet, add the rinsed lentils, vegetable broth, frozen mixed veggies, balsamic vinegar and remaining 1/2 teaspoon of salt. Stir until everything is well combined, then bring to a boil. Once boiling, lower to a simmer, cover and cook, stirring occasionally, for 25-30 minutes, or until the lentils are tender. 
• 10 minutes before the lentils are done cooking, preheat the oven to 400F and lightly grease a large casserole dish. I used a deep 9-inch pie dish. 8x11 works great, too. 
• Once the lentil filling is cooked through, taste and adjust the salt and black pepper as needed. 
• Transfer the savory lentil filling to a large casserole dish. Top with the fluffy mashed potatoes and smooth out, creating some ridges with a fork. 
• Place the pie in the oven and bake for 20-25 minutes, or until the top of the mashed potatoes are lightly golden brown and crispy. To give them additional color, you can broil for 2-3 minutes at the end as well! 
• Cool the shepherd's pie for at least 10 minutes to set, then serve while warm, as desired. Enjoy! 

Storage Instructions

• Leftover shepherd's pie will keep for up to 5 days in the refrigerator when covered tightly. Feel free to store directly in the casserole dish, covered tightly with plastic wrap or tin foil. Or, transfer the leftovers to an airtight container. 

Freezing Instructions

• To freeze in individual servings (preferred): Divide the filling between 4-5 2-cup Souper Cubes. Top with the mashed potatoes and let cool to room temperature. Cover, and freeze for up to 2 months. Then, when ready to eat, transfer a 2-cup serving to a 5″ Stoneware Baking Dish and bake, covered, from frozen for 35-45 minutes at 350F.
• To freeze as a whole casserole: Assemble in a freezer-friendly casserole dish, then cover tightly with plastic wrap followed by a layer of aluminum foil. Freeze for up to 2 months. When ready to eat, allow to thaw overnight in the refrigerator, remove the layer of plastic wrap, then bake, covered, at 350F for 45 minutes to 1 hour, or until completely warmed through.