Preheat your oven to 350°F (175°C).

Grease a 9x9 inch baking dish and set it aside.

Dry Ingredients and Lemon Zest

In a mixing bowl, combine the all-purpose flour, granulated sugar, salt, and baking powder.

Zest both lemons using a zester or fine grater, and add the zest to the dry ingredient mixture. Give it a quick mix to distribute the zest evenly.

In a separate bowl, crack the eggs and beat them until they're frothy.

Add the softened butter to the eggs and whisk until the mixture is well combined and creamy.

Squeeze the juice from both lemons and add it to the egg and butter mixture.

Stir in the vanilla extract and mix until everything is incorporated.

Gently fold the wet ingredients mixture into the dry ingredients mixture until just combined. Be careful not to overmix; a few lumps are totally fine.

Gently fold in the fresh blueberries. They're like little juicy gems waiting to shine!

In a small bowl, mix together the brown sugar and ground cinnamon for the streusel topping.

Pour the melted butter over the sugar-cinnamon mixture and stir until it forms a crumbly texture.

Pour the batter into the greased baking dish, spreading it evenly.

Sprinkle the streusel topping over the batter, distributing it in an even layer.

Pop the baking dish into the preheated oven and let the magic happen. Bake for 40-45 minutes or until a toothpick inserted into the center comes out clean.

Once the Lemon Blueberry Buckle has baked to golden perfection, carefully remove it from the oven.

Let it cool for a bit before serving. This dessert is heavenly both warm and at room temperature.