In a small bowl, combine the crumbled blue cheese and sour cream and blend until smooth.
Cut the pita loaves in half crosswise, and spread about 2 teaspoons of the blue cheese mixture inside each of the 8 halves. Next line the pita with a slice of the muenster, then layer in the ham and the pear slices.
Working in 2 batches, heat 1/2 tablespoon of butter in a large pan over medium heat. Add 4 of the pita halves and cook until the pita is golden on the outside and the cheese has melted, about 2 minutes per side. Repeat with the remaining pitas and serve immediately.