Place all of the ingredients for the spinach pesto into a food processor and blend until smooth.

Next spread the butter or olive oil on one side of each piece of bread. Place the bread buttered side down in a skillet over low to medium heat. Layer the mozzarella on top along with a slice of tomato. Then grab another slice of bread, spread the pesto on the side that’s not buttered and place it on top of the other piece in the skillet.

After it’s cooked for about 3 minutes and the cheese starts to melt, flip the sandwich so that the uncooked side is facing down. Cook for another 2-3 minutes, until light golden brown on the outside. Serve immediately and enjoy!