Spread thin layer of butter on steaks; season both sides with salt and cracked pepper. Heat cast iron skillet over high heat. Sear each side of steaks for about 2 minutes, until surface is crusty and steaks are cooked to desired doneness. Set aside.
Add 1 tablespoon butter to skillet meat was cooked in; add onions and caramelize over medium-low heat. Add 1 tablespoon water to deglaze pan if necessary. In skillet, divide onions into 2 piles. Arrange blue cheese over onions. Cover hot skillet for 30 seconds to melt the cheese.
Butter both sides of bread slices and lightly toast both sides in another heated skillet until golden brown. Spread gorgonzola cheese on 1 side of each slice. Slice filets and spread over 2 bread slices. Using a spatula, place onion and cheese piles over filet slices. Arrange orange slices over cheese. Top with remaining bread slices.
- 3 tablespoons butter, softened, divided
- 2 filet mignon steaks, about 4 ounces each and 1-inch-thick
- 1/2 teaspoon salt, or to taste
- 1 1/2 teaspoons black pepper, coarsely cracked
- 1 large onion, thinly sliced
- 2/3 cup (4 ounces) Wisconsin Blue cheese, crumbled
- 4 thick slices crusty white bread
- 2/3 cup (4 ounces) Wisconsin Gorgonzola cheese, crumbled
- 4 small mandarin oranges or 1 large blood orange, seeds removed and sliced into rounds