Butter one side of a slice of bread.

Place buttered side down into a skillet on medium heat.

Spread half of the pesto onto the bread.

Place a slice of mozzarella on top, followed by a tomato & the other slice of cheese.

Spread the other half of the pesto onto the second piece of bread & place it onto the sandwich.

Butter the exposed side of the bread.

Cook on one side until golden brown, about 5 minutes.

Flip & cook on the second side for about another 5 minutes.