Preheat the oven to 400 degrees F. Prick the potatoes all over with a fork. Brush lightly with the oil. Roast on a sheet tray until tender, 50 minutes to 1 hour.
While still hot, split the potatoes lengthwise and scoop the potato flesh into a medium bowl, leaving a 1/4-inch shell all around. Season the insides of the potato shells lightly with salt and pepper. To the bowl with the potatoes, add the sour cream, half-and-half and butter. Use an electric hand mixer or potato masher and mix until almost smooth. Season with salt and pepper to taste. Stir in 1 cup of the cheese, the jalapenos and scallions. Mound into the potato shells. Sprinkle the tops with the remaining 1/2 cup cheese. Place on a baking sheet and bake until heated through and the cheese is browned and bubbly, about 20 minutes. Sprinkle with paprika and serve.