Pre-heat the oven to 200 °C (≈400 °F). Wash and pierce the sweet potatoes a few times with a fork and place them on a baking sheet. Bake for about 35-40 minutes or until tender when pierced with a knife.

Meanwhile, in a large skillet over medium heat, heat the olive oil. Add the garlic and sauté briefly until fragrant, then add the diced mushrooms. Cook until the mushrooms release their juices and become soft.

Add the chopped spinach to the skillet, season with salt and pepper, and cook until the spinach is wilted and everything is well combined. Remove from heat.

When the sweet potatoes are done, remove from oven and let cool slightly. Then slice each potato lengthwise (halving) and gently scoop a little of the flesh if you like to create room for stuffing (you may reserve the scooped flesh for another use).

Divide the spinach-mushroom mixture among each halved sweet potato, topping each with optional grated cheese. Return to the oven for an additional 5-10 minutes until cheese is melted (if used) and everything is hot.

Serve immediately, optionally garnished with fresh herbs (such as chopped parsley) or a drizzle of olive oil.