Place the potatoes on the prepared baking sheet and prick all over with a fork.
Drizzle the potatoes with olive oil and season with salt, pepper, and cumin. Rub the oil and seasoning into the potatoes using your hands.
Transfer the potatoes to the oven to bake for 1 hour, or until tender. Remove the baking sheet from the oven and set aside until the potatoes are cool enough to handle.
While the potatoes are cooling, make the taco beef by heating olive oil in a medium skillet over medium-high heat.
Once hot, add the ground beef and taco seasoning to the skillet, stir to combine, and saute until cooked through, about 5 minutes.
Once the potatoes are cool enough to handle, slice them in half lengthwise.
Using a spoon, scoop out the potato flesh and place in a large bowl. Keep the potato skins on the baking sheet.
Make the mashed filling by adding the butter, garlic, chipotle peppers, sour cream, ½ cup cheddar cheese, scallions, salt, and pepper to the bowl with the potato flesh.
Using a potato masher, mix and mash the ingredients together until the filling is thoroughly combined.
Divide the filling evenly between the potato skins.
Top the filling with the taco beef.
Sprinkle the beef with the remaining ½ cup grated cheddar and return the stuffed potatoes to the oven.
Bake for 10 to 15 minutes, or until the cheese has melted, the skins have crisped, and the filling is hot throughout.
Serve the potatoes with tomatoes, onions, cilantro, scallions, and jalapeños, as well as any of your favorite taco condiments.