Line the bottom of an 8 inch square baking pan or baking sheet with foil or parchment paper and smooth with butter.
Place chocolate in a heatproof bowl. Place bowl in a medium sauce pot with a couple inches of water and bring 2-3 inches of water to simmer. Place the bowl on top and gently stir with a spoon or spatula until everything is completely smooth and melted.
Crush vanilla wafers and graham crackers in a food processor.
Chop ½ cup toasted hazelnuts and add to food processor.
Add jarred Dulce de Leche and melted bittersweet chocolate and pulse until smooth.
Press into square pan and then add ½ cup more hazelnuts on top.
Put baking sheet or pan aside until cooled to room temperature and then plan it in the refrigerator for 2-3. hours.
Once fully set break cut into brownie pieces and place in an air tight container.