Creating your Classic Blueberry Buckle can be straightforward if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9-inch square baking pan or line it with parchment paper.
2. Prepare Blueberries: In a small bowl, toss the blueberries with a tablespoon of flour to coat them lightly. This helps prevent them from sinking into the batter.
3. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
4. Cream Butter and Sugar: In a large bowl, using an electric mixer, cream together the softened butter and granulated sugar until light and fluffy.
5. Add Eggs and Vanilla: Beat in the eggs, one at a time, followed by the vanilla extract until well combined.
6. Combine Wet and Dry Mixtures: Gradually add the dry ingredients to the creamed mixture, alternating with the buttermilk. Mix until just combined.
7. Fold in Blueberries: Gently fold in the prepared blueberries, being careful not to overmix.
8. Prepare the Topping: In a small bowl, mix the brown sugar, ground cinnamon, and rolled oats together. This will create a crumbly topping.
9. Transfer to Pan: Pour the batter into the prepared baking pan, smoothing the top with a spatula. Sprinkle the topping evenly over the batter.
10. Bake: Place in the preheated oven and bake for 40-50 minutes, or until a toothpick inserted in the center comes out clean.
11. Cool: Once baked, remove from the oven and let it cool in the pan for 15-20 minutes before transferring to a wire rack to cool completely.

These steps will guide you in creating this incredible Classic Blueberry Buckle effortlessly.