Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.
Step 2: Wash the yellow squash thoroughly and trim off both ends. Slice the squash into uniform 1/4-inch thick rounds.
Step 3: Lay the squash rounds on a clean kitchen towel or several layers of paper towels. Gently press down with more towels to absorb as much excess moisture as possible; this is key for crispiness!
Step 4: In a large mixing bowl, combine the dried squash rounds with olive oil, garlic powder, onion powder, salt, and black pepper. Toss gently until all the squash slices are evenly coated.
Step 5: Arrange the seasoned squash rounds in a single layer on the prepared baking sheet. Ensure there is some space between each round to allow for proper air circulation and crisping; do not overcrowd the pan.
Step 6: Bake for 15-20 minutes, or until the squash is tender-crisp and the edges are lightly golden. Baking time may vary slightly depending on your oven.
Step 7: Carefully remove the baking sheet from the oven. Evenly sprinkle both the shredded sharp cheddar cheese and grated Parmesan cheese over all the squash rounds.
Step 8: Return the baking sheet to the oven and bake for another 5-7 minutes, or until the cheese is beautifully melted, bubbly, and golden brown with crispy edges.
Step 9: Remove from the oven and, if desired, garnish with fresh chopped parsley. Serve these crispy cheesy baked yellow squash rounds immediately and enjoy!