Preheat your oven to 400°F (200°C).
Wash the sweet potatoes thoroughly and pat them dry.
Prick each sweet potato several times with a fork.
Rub the sweet potatoes with olive oil and sprinkle with salt and pepper.
Place the sweet potatoes directly on the oven rack or on a baking sheet lined with parchment paper.
Roast for 45-60 minutes, or until the sweet potatoes are easily pierced with a fork.
Heat olive oil or butter in a large skillet over medium heat.
Add the sliced mushrooms and cook, stirring occasionally, until they are softened and browned.
Season with salt, pepper, and garlic powder.
Carefully slice each roasted sweet potato lengthwise, being careful not to cut all the way through.
Gently fluff the inside of the sweet potato with a fork.
Spoon the creamy mushroom and spinach filling into the sweet potatoes.
Top with a sprinkle of Parmesan cheese or your favorite toppings.
