5 ounces unsalted butter
5 ounces sugar
5 ounces all-purpose flour
1 large egg yolk
7 ounces pecans
3 ounces hazelnuts (toasted and skinned or purchased skinned)
Using a knife, coarsely chop the pecans. Using the blade of the knife, smash the skinned hazelnuts, then chop coarsely.
In an electric mixer, cream the butter and sugar together until blended and fluffy. Add the egg yolk and mix well. Mix in the flour, followed by the pecans and hazelnuts. Mix on full speed for 2-3 minutes to break down the nuts a little. Remove the dough and roll it into a log or logs, each about 2 inches in diameter. Wrap in plastic wrap and refrigerate 1-2 hours or overnight.
Preheat the oven to 325 degrees.
Remove the wrap and cut the log into ¼ inch thick slices and place on a baking sheet lined with parchment or a Silpat. Bake 15-20 minutes until slightly golden.
Resist temptation and cool completely before eating!