01 - Place pistachios in a bowl and cover with water. Soak overnight or for at least 6 hours. Drain and rinse thoroughly.
02 - Combine soaked pistachios, 3 cups filtered water, vanilla extract, maple syrup or honey, and a pinch of sea salt in a blender. Blend until exceptionally smooth.
03 - Pour the blended mixture through a nut milk bag or fine mesh sieve into a pitcher, extracting as much liquid as possible. Discard or reserve the pulp for another use.
04 - Transfer pistachio milk to a saucepan. Warm gently over medium heat, whisking until hot but do not allow to boil. Adjust sweetness to preference if desired.
05 - Brew espresso or strong coffee using an espresso machine or coffee maker.
06 - Pour hot pistachio milk into serving cups, reserving some froth. Top with espresso and stir gently to blend. Spoon reserved froth on top and garnish with crushed pistachios if desired. Serve immediately.