To make the pesto spread, place basil leaves, pumpkin seeds, Parmesan, garlic and salt in a food processor. Process ingredients until they are well-blended and fairly smooth. Add mayonnaise and pulse until just blended. Set aside.
Heat oven to 375 F. Lightly coat a baking sheet with olive oil or cooking spray.
Coat one side of each slice of bread with cooking spray. Lay bread slices on baking sheet with coated side facing down. Spread 1 1/2 tablespoons of basil pesto mayo on each slice of bread. Place 1/4 cup mozzarella, 4 ounces of turkey and 2 slices of tomato on two of the bread slices. Top sandwich with the remaining two slices of bread.
Bake for 10 to 15 minutes or until sandwich is warmed through and golden brown. Cut in half and serve.