Preheat oven to 350˚F. Generously butter a 12-inch cast iron skillet.
In a small bowl, toss together the cranberries and 1/4 cup sugar. Set aside.*
In a large bowl, whisk together flour, baking powder, cinnamon and salt.
In a medium bowl, whisk together melted butter, milk, sugar, egg and vanilla. Add the milk mixture to the dry ingredients, stirring to combine.
Scrape the batter into the prepared cast iron skillet. Scatter the sugared cranberries over the top of the batter evenly.
Bake for 25 to 30 minutes, until golden brown. Serve warm or at room temperature (surprisingly awesome at room temp by the way!).
notes
*If the sugar isn't sticking well enough to the cranberries, you can add a scant 1/2 tsp to 1 tsp of water or simple syrup to wet the berries. Make sure the water or simple syrup is cold.