Begin by peeling and quartering the Yukon Gold potatoes. Place them in a pot of salted water and bring to a boil over medium-high heat. Cook for about 15-20 minutes or until they are fork-tender and easily break apart. Drain the potatoes and let them sit for a minute, allowing excess moisture to evaporate.

In a large mixing bowl, mash the drained potatoes until smooth. Add in butter and Greek yogurt, mixing until creamy and well combined. Season generously with salt to enhance the flavor.

Heat olive oil in a large skillet over medium heat. Sauté the shallots for 2-3 minutes until they become fragrant and translucent. Stir in the mushrooms and carrots along with the fresh rosemary and thyme. Continue cooking for about 5-7 minutes, or until the mushrooms are softened and the carrots are tender.

Stir in tomato paste and flour, cooking for another 2 minutes. Gradually pour in the red wine, allowing it to reduce slightly for about 3-4 minutes. Then add the vegetable broth, scraping the bottom to incorporate all the flavors, and stir until the mixture thickens, about 5 minutes.

Remove the bay leaf and any herb sprigs from the skillet. Stir in the frozen peas until evenly distributed throughout the filling. Pour the fragrant vegetable mixture into a baking dish, spreading it out evenly.

Dollop the creamy mashed potatoes on top of the vegetable filling, using a spatula to spread them evenly. Use a fork to create peaks on the mashed potato layer.

Preheat your oven to 350°F (175°C). Place the assembled pie in the oven and let it bake for about 15-20 minutes, or until the filling is bubbling and the top is lightly golden.

Allow the Vegetarian Shepherd’s Pie to rest for about 10 minutes before serving.