2 Spanish onions, thinly sliced
2 tablespoons butter, plus additional butter for plate
2 to 3 tablespoons water
6 small Idaho potatoes, peeled, thinly sliced (6 cups)
Salt and pepper to taste
2 tablespoons olive oil, divided
1 cup fresh parsley leaves, packed
4 1-ounce slices Wisconsin Limburger Cheese
1/2 cup panko bread crumbs
2 tablespoons shallots, chopped
2 pounds beef skirt steak
Heat oven to 450°F. Butter pie plate. Sauté onions in 2 tablespoons butter in large pan until they caramelize, adding a little water. Stir occasionally. In pie plate, layer 1/3 of potatoes; season with salt and pepper; drizzle with 1/3 of olive oil. Layer 1/3 of onions over. Repeat layers twice, drizzling top layer with remaining olive oil. Bake 40 to 50 minutes or until knife can pierce the cake easily. Cover with foil if onions become too brown.
In food processor, chop parsley until fine. Add cheese; pulse to break up. Add bread crumbs and shallots. Process until mixture forms a paste-like texture. Set aside.
Cut steaks into 4 portions; season with salt and pepper. Sear both sides of steak in skillet. Place in oven-proof pan. Bake in 450°F oven to desired temperature, 7 to 10 minutes. Spread Limburger mixture on top of steaks during last 2 minutes of baking.
Cut pie into wedges. Serve on plate with steak melts.