In the bowl of a stand mixer fitted with the paddle attachment, cream the butter on medium-high speed for one minute.
Add the confectioner’s sugar and the vanilla and mix on low speed until the sugar is incorporated.
Increase mixer speed to medium-high and mix for 2-3 minutes, stopping to scrape down the sides of the bowl as needed.
Mixture should be light and fluffy.
In a separate bowl, add flour and salt. Whisk to combine.
Reduce speed to low and slowly add in the flour mixture, 1/2 cup at a time until fully incorporated.
Once flour is mixed in well, add the chopped hazelnuts and mix on low speed for one minute until combined.
If dough is too dry to come together, add 1 TBSP of water at a time until it holds together.
Turn the dough out onto a well floured surface and use your hands to pat into a large ball.
With a sharp knife, split the dough into two pieces.
Roll each piece out on a large piece of parchment paper, lightly flouring the rolling pin as you go. Roll the pieces until they are about 1/4 inch thick.
Slide the dough on the parchment paper onto a large cookie sheet and freeze flat for 45-60 minutes.
Preheat oven to 350 degrees and line two baking sheets with parchment paper.
Remove dough from freezer and cut out shapes using a 2 inch round cookie cutter or biscuit cutter.
Use as much dough as possible and then gather the scraps and re-roll the dough 1/4 inch thick. Freeze again for 10 minutes before cutting out more cookies.
Transfer cut outs on to the prepared pans, about 2 inches apart. Cookies will not spread much.
Bake for 11-13 minutes or just until edges turn golden brown.
Remove from oven and cool on baking sheets for 10 minutes.
Transfer cookies to a baking rack to cool completely.
Once cookies are cool, prepare the chocolate.
In a medium bowl over a double boiler, melt the chocolate over medium-low heat,
Stirring often. Remove from heat once chocolate is melted and smooth.
Dip cooled cookies halfway into the melted chocolate and then rest the cookie on a baking rack.
Before chocolate is fully set, top with finely chopped toffee and more hazelnuts if desired.
Allow cookies to set for 30 minutes.
*Store cookies tightly wrapped in a cool, dry place.
**Makes 40 2-inch cookies
***Cookies may be frozen before dipping in chocolate. Dough may be tightly wrapped and frozen.
