Preheat the oven to 350 degrees F and butter an 8-inch skillet or baking dish that is safe to use in the oven. Keep it aside.
Press the berries with your hands or the back of a fork to extract the juices, then mix ⅓ cup of brown sugar into it. Reserve.
In a medium-sized bowl, whisk together the flour, melted butter, remaining ⅓ cup of brown sugar, milk, and salt and whisk until smooth. Add the baking powder and whisk gently. Pour the batter into the greased skillet baking dish and spread it evenly in the corners using a rubber spatula.
Pour the strawberries and all their juice over the top of the cake batter. Bake in the oven for 20 to 25 minutes, or until a toothpick comes out clean in the center.
Take it out of the oven and let it cool for 3 to 5 minutes before serving it in bowls. Serve warm with ice cream.
Notes
Fresh strawberries are best, but you can use frozen ones too. Just thaw them completely and drain off excess liquid first, or the cake will be too soggy.
You can bake it a few hours ahead and warm it in the oven before serving. But for best texture, it’s magic right out of the oven.
If you don't have a cast iron skillet, an 8-inch oven-safe baking dish works just as well. Glass or ceramic is fine, just don’t use non-stick metal.
Cover loosely with foil and warm in a 350°F oven for 5-10 minutes. A splash of milk or cream on top before reheating helps, too.
To double the recipe, use a 9x13 dish or a large skillet. Add 5-10 minutes to the bake time and keep an eye on it.