- 8 slices white sandwich bread
- 4 tablespoons unsalted butter, room temperature
- 1/2 small sweet onion, sliced into 1/8-inch-thick rounds
- Flaky sea salt
- Coarsely ground black pepper
- Chopped parsley (for serving)
- A 3 1/2-inch-diameter cookie cutter
- Using cutter, punch a round from each slice of bread. Spread both sides with butter and top 4 rounds with 2 onion slices each; season with salt and pepper. Close sandwiches.
- Heat a large skillet, preferably nonstick, over medium-high and cook sandwiches until golden brown, about 2 minutes per side (onion will soften slightly). Top with parsley and more salt.