1. Fill a large pot halfway with water, place on the stovetop over high heat, add 1 teaspoon salt, and cover to bring to a boil. Once the water is boiling, add the potatoes and cook uncovered for 15-20 minutes, or until fork tender. Strain potatoes, reserving 1 cup of the potato water, and add the strained potatoes back to the pot with 3 tablespoons butter or ghee. Season with salt and pepper to taste and add a half cup of the potato water. Mash the potatoes, stir, and add the remaining potato water. Taste and season with salt and pepper if needed. Cover and set aside.
2. While the potatoes are cooking, start the onion gravy. Cut the onion in half lengthwise and then into ¼-inch slices. Add the remaining tablespoon of butter or ghee and 1 tablespoon olive oil to a skillet over medium-low heat. When the skillet is hot, add the onion. Cover and cook for 3-4 minutes undisturbed. Uncover, stir, reduce heat to low, and continue cooking uncovered, stirring frequently until onion has softened and browned, 10-15 minutes. Add the broth and Worcestershire sauce, stir to combine, increase heat to medium and bring to a light-bubbling simmer. Allow gravy to simmer until the gravy has reduced by half (watch closely and reduce heat if needed to prevent burning). Reduce heat to low (or remove from heat to prevent further evaporation) until ready to serve. 
3. Preheat oven to 350° F.  
4. To assemble the casserole: Add the remaining tablespoon of olive oil to a three-quart (13 x 9 x 2-inch) Pyrex baking dish and swirl to coat the bottom.   Add one half to three-quarters of the container of spinach to evenly fill the dish; use a large serving spoon to spoon the potatoes on top of the spinach (start down the center and gently spread over the spinach with the spoon). Note: Leave about 1 to 1 ½ inches of spinach uncovered around the edges of the pan. Spoon the onion gravy over the mashed potatoes and evenly spread the brat slices over the gravy. Spoon the sauerkraut over the spinach, around the edges of the dish. Cover with foil and place in the oven for about 5 minutes. Pull from oven, add the remaining spinach around the edges (the spinach will have wilted making room for the rest of the container), re-cover, and place back in the oven for another 4-5 minutes, or until the spinach is completely wilted.
5. When the spinach is wilted and the casserole is steaming hot, it is ready to serve. Serve with extra sauerkraut and mustard on the side.
6. Note: This recipe is outdoor grill friendly. Preheat the grill to 350-375° F. and preheat an 11-inch cast iron skillet for approximately 10 minutes before starting step number 2-cooking instruction. Once step 2 (the onion gravy) is done, use a long-handled ladle to scoop the gravy into a small pot or bowl. Follow instruction number 4 to assemble the casserole in the same cast iron skillet used to make the onion gravy and allow it to finish cooking on the grill. See step number 5 for serving.  

Beer Pairing

Recommended Beer Style: Pale Ale

• Samuel Smith Pale Ale