2 cups hazelnuts
1 1/2 cups sugar
1 cup buttermilk
1/2 cup lighth brown sugar, packed
1/2 cup light corn syrup
1 teaspoon baking soda
1/2 teaspoon salt
1 stick unsalted butter
1 tablespoon coffee liqueur (optional)
1 teaspoon vanilla
Preheat oven to 375 degrees. Line 2 baking sheets with parchment paper. Coat a line of butter around the inside of the 8 quart heavy bottomed pot three quarters of the way up the side.
Toast hazelnuts for 12-15 minutes in oven, remove from oven and skin; set aside to cool.
Combine sugar, buttermilk, brown sugar, syrup, baking soda and salt in prepared pot over medium heat until sugar dissolves and mixture starts to boil. Cover with tight fitting lid for 1-2 minutes to dissolve any sugar crystals on the side of the pot. Uncover, insert candy thermometer and boil mixture, sitrring gently and frequently until soft ball state 240 degrees.
Off heat, stir in butter, coffee liqueur and vanilla (it will sputter) until butter melts. Let mixture stand 10-20 minutes (depending on humidity) until it resembles thick caramel. Stir in toasted hazelnuts and beat candy with a wooden spoon until creamy and no longer glossy, 3 minutes. Spoon onto prepared baking sheets and allow to set 30-35 minutes. Store between layers of wax paper in a sealed container up to 2 weeks.