Preheat the oven to 425 degrees.
Line a baking sheet with aluminum foil. Spray with cooking spray.
Brush the outside of the potatoes with oil. Season with salt and pepper.
Bake the potatoes for 15-20 minutes until you can easily pierce the potatoes with a fork. Remove them from the oven and allow the potatoes to cool until you can handle them, about 15 minutes.
Carefully slice the potatoes in half lengthwise.
Gently scoop out the center of each half. Leave about a 1/4-inch border so the skins keep their shape. Save the inside of the potatoes for another use.
Gently spoon one heaping teaspoon of the pimento cheese into the center of each potato.
Top each with the shredded cheddar cheese.
Reduce the oven temperature to 350 degrees F.
Return the potatoes to the oven. Bake until heated through and the cheese is melted, about 5-10 minutes.
Serve hot. Garnish with green onions if desired.