In a small bowl, combine the ingredients for the Caesar spread, stirring them together with a spoon. If you don’t want little chunks of anchovies in the spread, you can mash them in with the back of a fork.

Turn the broiler on to high. Add the four slices of toasted bread to a baking sheet. Top the bread with the Parmesan and mozzarella cheese, dividing evenly between the four slices. Melt the cheese under the broiler, watching it carefully until the cheese is bubbling, approximately 30 seconds to 1 minute.

Remove the bread from the oven and build your sandwiches. Spread some of the Caesar spread on each slice of bread. Add sliced chicken to the bottom slices, followed by a layer of chopped romaine lettuce. Top with the remaining slices of bread. Serve immediately with any leftover caesar spread.