Step 1

Arrange a rack in the middle of the oven and heat to 450°F. Place the broccoli on a rimmed baking sheet. Drizzle with the oil, season with the salt, garlic, and several grinds pepper, and toss to combine. Spread into an even layer. Roast until tender and charred in spots, 15 to 18 minutes.

Step 2

Stir the mayonnaise and Sriracha together in a small bowl. Divide evenly among the slices of bread and spread to the edges. Divide the saurkraut between 2 of the slices, followed by the roasted broccoli. Top each with 2 slices of cheese. Finish with remaining bread slices spread-side down to close the sandwiches. Spread half of the butter onto the top of each sandwich.

Step 3

Heat a large skillet over medium heat until hot, about 4 minutes. Place the sandwiches butter side down in the pan. Cover with a second large, heavy skillet, preferably cast iron. Press down on the skillet so that it smushes the sandwiches (alternatively, press down firmly with a flat spatula). Cook until the bottoms are browned and crispy, 3 to 4 minutes.

Step 4

Uncover and spread the tops with remaining butter. Flip the sandwiches, then place the skillet on top again and press down. Continue cooking until the cheese is melted and the bottoms of the sandwiches are golden brown, 3 to 4 minutes more. Transfer to a cutting board, cut each sandwich in half, and serve immediately.