Puree spinach leaves in blender with 1/4 cup water until smooth and liquid. Combine flour and salt thoroughly. Add pureed spinach a little at a time and slowly incorporate with your hands until you have bread dough consistency. Place in an oiled bowl and cover with a damp cloth. Refrigerate for at least an hour.
Divide dough into eight equal portions and place on oiled surface. Place well seasoned skillet on medium heat. Meanwhile, roll out one portion of paratha dough 1/8 inch thick. Brush with oil and lay oiled side down on hot skillet. Cook until brown. Brush upside of paratha with oil and turn over with wide spatula. Let brown and flip again to assure even cooking. Remove from skillet, brush with butter and fold in half. Repeat with rest of portioned dough. Serve warm.