Place frozen rolls on baking sheet and cover with plastic wrap. Set aside 3-4 hours until dough has defrosted and doubled in size.
Once dough is ready, press each roll into a flat 4" circle with your fingers. Preheat oven to 350 degrees.
Mix garlic salt, cream cheese, mayo, parmesan, mozzarella, spinach and pepper in medium bowl until combined.
Place 1 heaping teaspoon of cheese mixture into center of each roll and fold dough around filling, pinching edges to completely enclose. Shape into a ball and place back on parchment-lined baking sheet.
Bake 15-20 minutes and remove from oven. Brush with melted butter and sprinkle with garlic salt. Serve while still warm and enjoy!