Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the mashed avocado, melted coconut oil (or butter), coconut sugar, egg, and vanilla until smooth.
Add the matcha, almond flour, oats, baking powder, and salt. Stir until a soft dough forms.
Gently mix in the chopped pistachios. The dough should be thick and scoopable.
Scoop the dough onto your prepared baking sheet (about 1–1.5 tablespoons per cookie). Flatten the tops slightly with your fingers or a spoon.
Bake for 10–12 minutes, or until the edges are set and the centers look soft but not wet.
Let the cookies cool on the baking sheet for at least 5 minutes before transferring them to a rack. They firm up as they cool.