01 - Preheat oven to 400°F. Scrub sweet potatoes thoroughly and pierce each several times with a fork to allow steam to escape during baking.
02 - Arrange sweet potatoes on a parchment-lined baking tray. Bake for 45-50 minutes until tender when pierced with a knife.
03 - While potatoes bake, heat olive oil in a skillet over medium heat. Add minced garlic and sauté until fragrant, approximately 30 seconds.
04 - Add spinach to the skillet and stir constantly until wilted, 2-3 minutes. Season with salt, pepper, and nutmeg if using. Remove from heat and let cool slightly.
05 - In a mixing bowl, combine ricotta, sautéed spinach, Parmesan, and milk. Stir until creamy and thoroughly blended. Adjust seasoning as needed.
06 - Once baked, let sweet potatoes cool for 5 minutes. Make a lengthwise slit down the center of each potato without cutting completely through. Gently fluff the interior flesh with a fork.
07 - Divide the spinach ricotta filling evenly among the potatoes. Return to oven for 5 minutes if desired to heat through. Garnish with chopped parsley and serve warm.