Grind the chopped walnuts with the sugar and salt until the mixture looks like fine beach sand. Stir the yolks into this mixture until thoroughly moistened. Blend in the melted butter, cover and chill for 15 minutes.
Lightly grease and flour the inside of a tart pan (with a removable base), shaking out any residual flour.
With your fingers, press the walnut dough into the pan and up the sides.
Bake for ten to fifteen minutes, until the edges are a golden brown. Cool on a baking rack.
Place chocolate pieces in a glass bowl and set over a pan of simmering water.
Scald 1¼ cup heavy cream with ⅛ tsp of salt.
Pour cream over the chocolate and stir until smooth.
Whisk in butter, one tablespoon at a time.
Cool slightly and pour the cool ganache into the walnut crust. Allow to cool for another fifteen minutes. Do not refrigerate until the filling is room temperature.
PEPPERMINT CREAM INSTRUCTIONS:
Beat the cream cheese until soft with the whisk attachment of a mixer.
Slowly beat in the sugar.
Whisk in the heavy cream and continue to beat until relatively stiff.
Whisk in 1 Tbsp vanilla and 1 tsp peppermint extract, beating until the cream looks like a pastry cream.
Chill for two hours.
With an offset spatula, spread a thin layer of peppermint cream over the ganache, but thick enough that none of the chocolate shows through the cream.
Sprinkle lightly with the crushed peppermint candies.
Chill until set.
Prior to serving, allow the tart to sit out at room temperature for 30-45 minutes.
*Pecans are a suitable replacement, although the bold notes of the walnuts complement the chocolate and peppermint flavors in this recipe. If using salted, roasted walnuts, omit the ⅛ tsp salt in the ingredients list.
**Crushed peppermint candies are available in stores. When making at home, I prefer the soft mint peppermint puffs, which grind to a powder more easily and provide a more pleasant, chewier powder.