Preheat the oven to 350°F (180°C). Line a large baking sheet with parchment paper. Slightly oil with cooking oil spray. Set aside.
Place the pistachios in the bowl of a small food processor or coffee grinder. Pulse a few times to form a fine pistachio ground.
In a large mixing bowl, add all the ingredients: ground pistachios, almond flour, oil, lemon juice, lemon zest, maple syrup, vanilla extract, and almond extract.
Stir with a spoon at first, then use your hands to squeeze all the ingredients together until it forms the cookie dough batter.
Form 12 cookie dough balls of the same size - about 1 ½ tablespoons of batter each.
Lightly oil your hands, and roll the cookie dough in your hand to form a smooth cookie dough ball. Place each cookie dough ball on the prepared cookie sheet, leaving a 1-inch space between each cookie ball.
Press in the middle of each cookie dough ball to form a deep cavity in the center of each cookie.
Fill each thumbprint cookie with ½ teaspoon jam.
Bake for 12-14 minutes until the sides of the cookies are slightly golden brown.
Cool 10 minutes on the cookie sheet, then refill with a bit more jam in the middle if needed.
