Preheat oven to 400º.

Wash potatoes and place in a medium saucepan filled with cold water. Place on stove over high heat and bring to a boil. Continue to boil anywhere from 12 - 20 minutes, or until easily pierced with a fork. *You can move ahead with the next steps of the recipe while the potatoes are cooking, especially if you have a proper mise en place setup (every ingredient measured and prepared [chopped, diced, etc.]*. Meanwhile, setup an ice bath--fill a large bowl with ice water, ensuring not all the ice melts. When the potatoes are cooked properly, remove with a slotted spoon and drop into the ice bath. After about a minute or so, remove the skins from the potatoes (they should come off easily after being boiled and shocked in the ice bath) and quarter. In a glass or microwave-safe measuring cup, microwave 2 tablespoons butter and 1/3 cup milk until butter is melted and milk is hot. Pour into potatoes and mash or whip until the desired consistency. Taste and season with salt. Add a bit more milk if you like.

While the potatoes are cooking, you can move ahead. In a large skillet (cast iron or otherwise), melt 2 tablespoons butter over medium heat. Add the onion and sauté until translucent. Then, add in the garlic and mushrooms and sauté, stirring constantly, until the garlic is aromatic, the mushrooms are "sautéed", and the onion is golden.

Add the lentils and their liquid and bring to a gentle simmer. Stir in the wine, soy sauce, rosemary and dried spices. Cook gently for 5 minutes. Combine the cornstarch a small amount of water--just enough to dissolve it--in a small bowl then stir into the lentil mixture.

Add in spinach a bit at a time and cook until just wilted. Remove from the heat, taste, and adjust seasonings. Fish out the fresh rosemary stalk and discard.

Lightly oil a 2-quart (preferably round) casserole dish, two deep-dish pie plates, or ignore if you plan to use your large cast iron skillet that you've been cooking in. If using a separate dish, scatter the breadcrumbs evenly over the oiled bottom. Pour in the lentil mixture, then spread the potatoes evenly over the top. If using two pie plates, divide each mixture evenly between them. If using cast iron skillet, sprinkle the breadcrumbs over the top of the lentil mixture for fun (it's super fun, I promise), or skip that part if you desire. Spread the potatoes over the top of the lentil mixture.

- 35 minutes or until top becomes slightly crusty and golden. If desired, melt a little butter and brush the top of the potatoes with it about 20 minutes into the baking process. When done, remove from the oven and let stand 5 - 10 minutes, then cut into wedges and serve. Yum yum!