Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.

Slice the zucchinis lengthwise into thin, flexible ribbons using a mandoline or vegetable peeler. Discard the outer skin-only slices.

Lay the strips on paper towels, sprinkle lightly with salt, and let sit for 10 minutes. Pat completely dry with clean paper towels.

In a medium bowl, thoroughly stir together the ricotta cheese, shredded mozzarella, minced garlic, fresh thyme leaves, and a tiny pinch of salt and pepper.

Lay a zucchini ribbon flat, place one tablespoon of the cheese mixture at one end, and roll it up tightly. Repeat for all remaining strips.

Set up two small shallow bowls. Beat the egg in the first bowl. Mix the Panko breadcrumbs and grated Parmesan together in the second bowl. Dip the top and sides of each roll into the egg, then roll in the breadcrumb mixture until coated.

Arrange the rolls seam-side down on your prepared baking sheet. Spray the tops lightly with olive oil cooking spray. Bake for 15 to 18 minutes until the zucchini is tender and the crust is deeply golden brown. Garnish with fresh thyme and serve warm.