In a medium pan, melt 4 tablespoons of butter over low to medium heat. Add 1 cup of crushed vermicelli, stirring continuously for about 10 minutes until golden brown and aromatic.

In a mixing bowl, combine the cooled vermicelli with 1 cup of pistachio butter and if desired, 2 tablespoons of tahini. Stir until fully blended.

Melt ½ cup of white chocolate in a microwave-safe bowl in 30-second intervals, stirring in between until smooth. Drizzle half of the white chocolate in chocolate molds, optionally mixing in green food coloring.

In a heatproof bowl set over simmering water, combine ½ cup of milk chocolate and ½ cup of dark chocolate. Stir for about 5–7 minutes until melted and smooth.

Pour the tempered milk and dark chocolate into each mold, covering the sides. Allow to set at room temperature for 20–30 minutes.

Spoon the crunchy pistachio filling into each mold, mounding it slightly in the center.

Brush the edges of the filled molds with additional melted chocolate and close the molds tightly. Refrigerate for at least 1 hour.

Once removed from the fridge, gently pop out the Crunchy Pistachio Chocolate Bars and serve.