Preheat the oven to 150°C (302°F) and spread the pistachios on a baking sheet lined with parchment paper or a Silpain mat. Roast them for 8 minutes to intensify their flavor. The pistachios should not brown.

First, blend the pistachios alone to reduce them to a fine powder.

Add the sugar and blend again until you get a homogeneous texture.

Stop the food processor to scrape down the sides, then continue blending until you get a smooth, runny paste.

Add oil if necessary to help liquefy the paste.

To enhance the flavor, incorporate the bitter almond extract at the end of preparation (optional).

This paste can also be made without sugar according to your preferences.

Note: If you're using a not very powerful food processor, stop it from time to time to let the motor cool down and avoid overheating.

Pour the pistachio paste into a glass jar and seal it tightly.