These sandwiches are packed with flavor, thanks to green olives, tomatoes and two kinds of cheese. A cast-iron skillet makes the bread nice and toasty, but an electric panini press would also do the trick.
1/4 cup extra-virgin olive oil, plus more for brushing
1 medium red onion, thinly sliced
2 garlic cloves, minced
1 head of broccoli (about 1 1/4 lbs), tender stems and florets only, coarsely
1 cup pitted green olives, coarsely chopped
2 medium tomatoes, coarsely chopped
Salt and freshly ground pepper
2 cups shredded sharp cheddar (6 ounces)
2 cups shredded Monterey Jack (6 ounces)
8 pocketless pitas
In a large skillet, heat the 1/4 cup of olive oil. Add the onion and garlic and cook over moderate heat until softened, about 4 minutes. Stir in the broccoli, cover and cook over moderate heat until just tender, about 4 minutes. Stir in the olives and tomatoes and season with salt and pepper.
Brush one side of the pitas with olive oil. Mix the chedder and Monterey Jack cheese. Heat a cast iron skillet, remove from the heat and add one of the pitas, oiled side down. Scatter 1/2 cup of the cheese on the pita. Spoon one-fourth of the broccoli mixture over the cheese and top with another scatter another 1/2 cup of cheese. Top with another pita, oiled-side up and return the skillet to the heat. Set a small heavy skillet on top of the sandwich and cook over moderate heat until pita is browned and crisp and the cheese is melted, about 2 minutes per side. Transfer the sandwich to a work surface. Repeat with the remaining pitas, cheeses and filling. Cut the sandwiches into 4 wedges and serve right away.
The broccoli filling can be refrigerated overnight. Bring to room temperature before using.