Preheat the oven to 400℉ and prepare a 9X13 in baking dish by spraying it with cooking spray. Set it aside.
In a small bowl whisk together the garlic powder, salt, dried basil, dried thyme, and pepper.
In a large skillet over medium high heat, heat oil and sauté the onions until they soften. Add the zucchini into the skillet and season with lemon juice, and the whisked seasonings.
Turn the heat on low and simmer for 10 minutes or until the zucchini is soft, stirring occasionally.
In a separate small bowl, whisk the cornstarch into the half and half to combine completely. Don't fret if there's a few little lumps.
Stir the cream mixture into the suzzhini and stir continuously until everything thickens.
Pour the zucchini into the prepared baking dish and set aside.
In a small bowl, combine and mix the Panko breadcrumbs and Parmesan cheese. Spread the breadcrumb mixture over the zucchini in the baking dish.
Melt the butter in a microwave safe bowl. Pour the butter over the cheesy breadcrumbs.
Cover with aluminum foil and bake for 25 minutes.
Take off foil and return the pan to the oven and bake for an additional 10-15 minutes or until the top turns golden brown and the sides are bubbly.
Garnish with freshly chopped parsley then plate and serve. It's best when the baked zucchini is served warm.