Nutella Stuffed Deep Dish Churro Skillet Cookie



½ cup light butter, softened (or your spread of choice)
½ cup light brown sugar (or muscavado)
⅓ cup natural sweetener/sugar of choice
1 tablespoon vanilla extract
1 egg
1 cup flour (plain, all purpose or light spelt)
½ teaspoon baking soda
⅓ teaspoon salt
⅔ cup nutella, melted and divided (or any hazelnut cacao spread)
2 tablespoons cinnamon sugar, divided
2 tablespoons low fat milk (or almond milk)*