Heat a large skillet over medium heat and a pat of butter. Spread the outside of each slice of bread with butter and arrange the cheddar and havarti cheese on each side of the sandwich. Sprinkle the parmesan and everything spice over both buttered sides of the bread, pressing the spice mix gently into the bread to adhere. Place the sandwiches, one at a time, in the skillet and cook until golden on each side, about 4-5 minutes per side.