Start with preheating the oven at 350-degree F.
Prepare a 6-inch baking pan by greasing with oil or butter.
Now, take a mixing bowl and cream the butter with the help of a stand mixer or hand mixer.
Once the butter is fluffy, add sugar and egg to the butter and whisk it until the mixture is pale.
Add vanilla and lemon zest and gently fold.
In a separate medium-sized mixing bowl, whisk the dry ingredients; 1 ½ cup of flour, baking powder, and salt.
Gradually add the flour mixture to the butter and egg mixture, lemon juice, and buttermilk. Fold the mixture until no lumps are visible.
In a separate bowl, toss the blueberries and remaining 1/3 cup of flour.
Add the blueberries to the cake batter and fold them gently in.
Pour the cake batter into the prepared pan.
Bake the cake for 30 to 35 minutes. Test if the cake is cooked correctly by pocking in a toothpick and checking if it is clean.
Take the bake out, sprinkle some granulated sugar over the cake, and broil for 3 to 5 minutes until sugar is bubbly and caramelized.
Let the cake rest at room temperature for 15 to 20 minutes.
Serve and enjoy with maple syrup.