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, filtered water, vanilla extract, maple syrup or honey, and sea salt. Blend on high speed until smooth. 
 03 -  Strain the blended pistachio mixture through a nut milk bag or fine mesh sieve into a pitcher. Set aside solids for baking or discard. 
 04 -  Transfer strained pistachio milk to a saucepan and warm gently over medium heat, whisking until hot but not boiling. Sweeten to taste if desired. 
 05 -  Prepare espresso or strong brewed coffee using an espresso machine or coffee maker. 
 06 -  Divide hot pistachio milk between cups, reserving some froth. Add espresso to each cup and gently stir to combine. 
 07 -  Top with reserved milk froth and garnish with crushed pistachios if desired. Serve immediately.