Preheat the oven to 425°F (220°C).

Scrub the potatoes under cold water and pat them dry. Prick each potato several times with a fork, then rub them with olive oil and sprinkle with salt and black pepper.

Place the potatoes directly on the oven rack and bake for 45-60 minutes, or until tender when pierced with a fork.

While the potatoes are baking, heat a large skillet over medium heat. Add the sliced mushrooms and sauté for about 5 minutes until they are golden brown.

Add the chopped spinach to the skillet and cook for an additional 2-3 minutes until wilted. Remove from heat and set aside.

Once the potatoes are done, remove them from the oven and let them cool for a few minutes. Cut a slit down the center of each potato and gently squeeze the ends to open them up.

Spoon the sautéed spinach and mushroom mixture into each potato, then top with shredded cheddar cheese.

Return the stuffed potatoes to the oven for an additional 5-10 minutes, or until the cheese is melted and bubbly.

Serve the baked potatoes hot, topped with a dollop of sour cream and a sprinkle of chopped green onions.