Cut the ends off of each zucchini. Slice zucchini down the middle, lengthwise. Use a spoon to scoop out the middle (flesh) of the halved zucchinis. Place skin side down on a parchment lined rimmed baking sheet.
In a small bowl add spinach, basil, ricotta, garlic, egg, salt and pepper. Mix thoroughly with a spoon.
Line zucchini with marinara sauce. Divide ricotta mixture evenly between the 4 halved zucchinis. Top each zucchini boat with parmesan cheese and panko breadcrumbs.
Bake for 20 minutes. Turn oven up to broil and allow the tops of the zucchini boats to turn golden brown, watch carefully as not to burn.
Remove from oven, garnish with additonal chopped basil and serve immediately.
Recipe by Good Thyme Kitchen at https://www.goodthymekitchen.com/italian-stuffed-zucchini-boats/