Preheat your oven to 425 degrees F ( 220 degrees C ) and line a baking sheet or two with parchment paper, non-stick spray coated aluminum foil or a silpat mat.
Prepare your yellow squash, wash each squash and trim the ends. Slice in thin, even sized slices so that they cook evenly and are done at the same time. I use a mandoline to cut the slices so they are just under ¼ inch in thickness.
Spread sliced squash on your baking sheet(s) in a single layer. Sprinkle with seasoning, garlic salt and pepper.
Grate Parmesan and spoon it onto the yellow squash rounds. Dollop grated Parmesan cheese in the center of the slices, or use the back of your spoon to push the cheese out to the edges of each slice.
Bake in the center of your oven at 425 degrees F ( 220 degrees C ) for approximately 15 minutes, or until golden browned on the tops and the cheese has melted.