Preheat oven to 350°F. While oven is preheating, add butter to an 8 inch cast iron skillet (or 8x8" baking dish), and add it to the oven for a few minutes so the butter will melt as the oven preheats.
When the butter is melted, remove the skillet from the oven and set aside.
Slice the stem end off of each strawberry, then slice the berry in half lengthwise. Set aside.
In a mixing bowl, add the brown sugar, whole milk, lemon zest, lemon juice, and vanilla extract. Whisk until smooth and combined.
Add flour, baking powder, and salt, whisking until you have a mostly smooth batter. A few lumps are okay.
Pour the batter into the skillet with the melted butter, then sprinkle with sliced strawberries. Don't stir, just leave the berries scattered over the top of the batter.
Sprinkle the granulated sugar over the top of the berries.
Bake in preheated oven for 45-50 minutes (55-60 minutes if using a baking dish instead of the skillet), or until the cobbler is golden brown, puffed up, and the juices are bubbly.
Let the cobbler cool for 15 minutes, then serve warm (or at room temperature) with vanilla ice cream if you prefer.
