01 - Place the pistachios in a bowl and cover with water. Soak overnight or at least 6 hours. Drain and rinse thoroughly.
02 - Combine soaked pistachios, filtered water, vanilla extract, maple syrup or honey, and sea salt in a blender. Process until fully smooth.
03 - Pass the blended mixture through a nut milk bag or fine mesh sieve into a pitcher. Discard solids or reserve for baking.
04 - Warm pistachio milk in a saucepan over medium heat, whisking until hot but not boiling. Adjust sweetness 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. Add espresso to each cup and stir gently until incorporated.
07 - Top each cup with froth and garnish with crushed pistachios as desired. Serve immediately.