Preheat oven to 375°F and put paper liners in a 12-cup muffin pan.
In a bowl, whisk together flour, baking powder, and salt.
In a large bowl, cream together butter and sugar until light and fluffy. Beat in orange zest until fragrant. Beat in egg, then stir in milk and vanilla.
Pour flour mixture into wet mixture and stir until combined, but do not overmix. Fold in cranberries.
Fill muffin pan wells about 3/4 full. Sprinkle sparkling sugar over the tops of the muffins, if using. Bake for 20-22 minutes, or until golden brown and a toothpick inserted in the center comes out clean.