Preheat the oven to 350°. Line a 9-inch square pan with parchment.
In a food processor with the S blade attached, process the pistachios, oats, and salt for about 30 seconds, until they start to form a meal. While the motor is still running, drizzle in the maple syrup and olive oil until the meal begins to come together into a crumbly, almost-wet dough.
Press the dough evenly into the pan and cover with coconut flakes and chopped pistachios if using. Bake 10 to 12 minutes, until the coconut is golden brown and the dough is cooked through. Set aside to cool.
Carefully lift the cooled dough out of the pan by holding two sides of the parchment. Cut into squares. Drizzle with honey if desired.
Recipe by Jessica Murnane from One Part Plant.