01 - Preheat oven to 400°F. Wash, scrub, and dry potatoes. Pierce several times with a fork, coat with olive oil, season with salt and pepper, and set directly on the oven rack.
02 - Bake potatoes for 50 to 60 minutes or until tender with crisp skins. For air fryer, cook at 375°F for 35 to 40 minutes, turning halfway through.
03 - While potatoes bake, heat olive oil or vegan butter in a skillet on medium. Sauté minced garlic for 1 to 2 minutes, add diced mushrooms, cook until softened—about 5 minutes—then stir in chopped spinach until wilted, about 2 minutes. Remove from heat.
04 - Once potatoes are cool enough to handle, halve lengthwise. Gently scoop out flesh, leaving about 1/4 inch shell. Transfer potato flesh to a bowl.
05 - Mash potato flesh with sour cream, shredded cheddar, milk, smoked paprika, and onion powder. Fold in sautéed vegetables. Season filling with additional salt and pepper if needed.
06 - Generously fill the reserved potato skins with the prepared mixture, slightly mounding each portion. Top with extra cheese if desired.
07 - Place filled potatoes on a parchment-lined baking sheet. Bake at 375°F for 15 to 20 minutes until tops are golden and bubbly. For air fryer, cook at 375°F for 10 to 12 minutes. For casserole method, arrange potatoes in a greased dish, optionally sprinkle more cheese, cover with foil, bake at 375°F for 15 minutes, then uncover and bake for 10 minutes more.
08 - Sprinkle potatoes with fresh chives. Serve immediately as a main course or a hearty side.