1In small bowl, mix mayonnaise and pesto.
2Spread 1 side of each bread slice with butter. Turn bread slices butter sides down; spread other sides with 1 tablespoon pesto mixture each. Top 8 bread slices with turkey, artichokes, tomatoes and cheese. Top with remaining bread slices, butter sides up.
3In sandwich grill or 12-inch skillet, cook sandwiches over medium heat 3 to 4 minutes, turning once, until bread is toasted and cheese is melted.