Twice-Baked Potatoes With Irish Cheddar

Ingredients

• 4 large russet potatoes, (about 1 pound each)
• 2 teaspoons olive oil, plus more for the pan
• 3/4 cup half-and-half
• 1/2 cup sour cream, plus more for serving
• 1 1/2 cups shredded irish cheddar cheese or your favorite cheddar, (about 7 ounces)
• 1/4 cup thinly sliced scallions, white and green parts (about 2 scallions)
• 2 tablespoons unsalted butter, melted
• kosher salt and freshly ground black pepper
• 1/4 cup grated parmigiano-reggiano
• 1 tablespoon thinly sliced scallions or chives