Place the potatoes in a large soup pot or Dutch oven and fill with water just enough to cover. Bring to a boil and cook until tender, then drain. Add the yogurt, salt, and pepper and mash to your liking.
Heat the oil in a large non-stick skillet. Sauté the onions, garlic, and carrots over medium heat for 3-4 minutes.
Add in the mushrooms and fresh herbs. Cook stirring occasionally until mushrooms start to slightly brown.
Stir in the tomato paste and flour. Add the broth/stock little by little, stirring continuously until the sauce starts to form.
Taste and season with salt and pepper; allow the sauce to simmer for about 10 minutes, or until it fully thickens.
Meanwhile, preheat the oven to 350F.
Stir in the peas, and balsamic vinegar and transfer to a baking dish. Spread over the mashed potatoes and bake at 350F for 18-20 minutes or until bubbly and slightly brown on top.
Allow the shepherd's pie to cool for a bit before transferring to plates. Serve and enjoy!
Notes
Potatoes: We use Yukon Gold for fluffy potatoes, but you can use russet or red potatoes instead. You may even use sweet potatoes. For a low-carb option, use mashed cauliflower.
Veggies: We suggest using fresh mushrooms and carrots, but you can also add frozen carrots or additional veggies as desired.
Herbs: Fresh herbs add the best flavor to this recipe, but if you only have dried they will work.
Make it vegan: Substitute the Greek yogurt for a dairy-free milk substitute.
Add lentils: If you're looking for more protein, try adding lentils.
Storage: Store in a sealed container in the fridge for 3-4 days. Reheat in the microwave or in the oven preheated to 350 degrees until warmed through.
Freezer instructions: Freeze after baking or make it ahead and freeze right before you bake. Allow it to cool, then wrap tightly in plastic and foil. Freeze for up to 1 month. To reheat, allow to thaw in the fridge overnight, then bake at 350 degrees until heated through, 20-30 minutes.