Preheat oven to 375. Line a large baking sheet with parchment paper.

Slice each potato in half lengthwise. Carefully scoop out pulp using a small spoon, leaving around 1/4 inch of the potato skin intact.

Arrange the skins on a baking sheet, and sprinkle with 1/2 TSP paprika.

Mash the potato flesh up until there aren't any big chunks left, then place in a large bowl. Add the mushrooms, pepper, spinach, onion, all-purpose seasoning, olive oil, and remaining paprika in, and stir until evenly coated. If the mixture seems dry, add a bit more olive oil.

Spoon the filling evenly into each skin. Shape the mixture into the skins as you scoop it in so that it doesn't overflow out of the potato skin.

Tent with foil and bake 35-40 minutes, until the veggies are soft. Add the cheese, and bake until the cheese is melted and the potatoes are crisp and golden (about 10 minutes).

Put the potatoes on a large platter and cool a bit before serving.