Vegetarian Potato Lasagna

Ingredients

• 2 cups water , salted
• 3 cups Baby Spinach , washed
• 2 cups low-fat ricotta cheese
• 1 bunch fresh flat-leaf parsley , chopped
• 1 lemon , zest of
• 1/2 cup parmesan cheese , freshly grated , divided
• 2 lbs russet potatoes , peeled and cut into rectangular blocks
• 1 tablespoon butter
• 2 cups marinara sauce , homemade or 2 cups marinara sauce , purchased
• salt
• pepper