Gather all your ingredients so that you have everything close at hand on the counter or table.
Prepare the Parmesan Butter
In a small bowl, mix together the softened butter, Parmesan cheese and dried parsley.
Make the Sandwiches
Slice pieces of sourdough bread 1/4"-3/8" thick. Spread prepared butter on one side of each piece of bread.
Place 4 bread slices, butter-side down on a preheated griddle.
Add approximately 1 1/2 ounces of sliced cheese to each piece of bread. (If desired, spread 1 tablespoon of pesto on the cheese.) Top with remaining piece of bread, butter-side up. Grill until one side is lightly brown.
Turn with a spatula and grill the other side until golden brown and cheese has started to melted along the edges.
If desired, cut in half with a sharp knife. Serve warm with your favorite soup. 4 servings.
Notes
*Unless otherwise indicated, all butter used on this recipe site is salted.