Creating the perfect Blackberry Pistachio Bars is simple when you follow these steps:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Line an 8×8-inch baking dish with parchment paper for easy removal.
2. Prepare the Oat Mixture: In a large bowl, combine the rolled oats, flour, brown sugar, and salt. Mix well to combine.
3. Add Wet Ingredients: Pour in the melted butter and vanilla extract. Stir until the dry ingredients are fully coated with the wet ingredients and form a crumbly mixture.
4. Press into the Pan: Take roughly two-thirds of the oat mixture and press it firmly into the bottom of the prepared baking dish. This will form the crust.
5. Layer with Blackberries: Evenly distribute the blackberries over the crust, ensuring they are scattered well.
6. Sprinkle with Pistachios: Sprinkle the chopped pistachios over the blackberries, ensuring an even distribution for flavor in every bite.
7. Top with Remaining Mixture: Crumble the reserved oat mixture over the top of the blackberries and pistachios, covering them lightly.
8. Bake: Place the baking dish in the preheated oven. Bake for 30-35 minutes or until the top is golden brown and the berries are bubbly.
9. Cool: Once baked, remove the dish from the oven and allow it to cool in the pan for 20-25 minutes. Then lift the bars out using the parchment paper and transfer them to a wire rack to cool completely.
10. Slice and Serve: Once cooled, cut into bars of your desired size.

By following these straightforward instructions, you’ll ensure your Blackberry Pistachio Bars turn out perfectly every time.