Preheat a large pan over low-medium heat (alternatively you can use a panini style press or a George-Foreman style grill). Grease the pan or panini grill with non-stick spray.
Mix the mayo and garlic in a bowl and spread it on both slices of bread. Layer with cheese, turkey, arugula, tomatoes seasoned with salt and pepper, then top with the other bread slice.
Place the sandwich in the pan covered with a lid or on the panini grill and cook until the bread is golden brown and the cheese has melted. (If using a pan, flip the sandwich over and repeat for the other side, you may need to grease the pan with more non-stick spray.)