Cut the butter into pieces and place them in the bottom of a 9×13-inch baking dish. Place the dish in the oven until the butter is melted.
In a large mixing bowl, stir together the blueberries, granulated sugar, lemon juice, lemon zest, and cinnamon until the blueberries are evenly coated.
Carefully remove the baking dish from the oven. Pour the blueberry mixture evenly over the melted butter.
In a separate bowl, whisk together the flour, granulated sugar, baking powder, and salt.
Stir in the milk until just combined, then stir in the vanilla extract.
Drizzle the batter evenly over the blueberry mixture.
Bake for 25–30 minutes, or until the batter is cooked through and the top is lightly golden brown.
Remove from the oven and let the cobbler rest for 5–10 minutes before serving.
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Notes
Make sure that the dough is done before removing the cobbler from the oven. The center of the dough should be set and not wet looking. The blueberries around the outside will be bubbly. I used fresh blueberries for this recipe. You can use frozen as well and if so, you do not need to thaw them out before baking. Refrigerate any leftovers in an airtight container for up to 1 week. This is best served warm so reheat the leftovers before serving.