Prepare your pan: Preheat your oven to 350 degrees F and slice the butter into pieces. Add the butter to a 9×13 inch baking dish. Place the pan in the oven while it preheats, allowing the butter to melt. Once melted, remove the pan from the oven.
Tip: Use a glass or ceramic pan for this recipe. Metal pans can react to the acidity in the blueberries and lemon, giving them an unpleasant metallic taste.
Prepare the blueberries: Add the blueberries, sugar, and zest to a bowl and stir to combine.
Prepare the batter: Mix the batter ingredients: flour, sugar, baking powder, and salt. Stir in the milk, just until combined. Pour blueberries over melted butter in the pan, drizzle the batter over the top, and sprinkle with a little bit of cinnamon.
Bake: Bake at 350 degrees for about 35–40 minutes or until lightly golden on top.
Time to Serve: I recommend serving the cobbler warm with a scoop of vanilla ice cream whipping cream if desired.