Make the filling first, as it needs time to set; beat together the filling ingredients and refrigerate until needed.

TO MAKE ORESHKI: In a medium bowl beat the eggs and sugar until pale and frothy; set aside.

In a separate small bowl beat the butter until smooth then add the mayonnaise and mix to combine. Set aside.

Dissolve the vinegar with baking soda and set aside.

Sift together the flour and cornstarch into a large bowl. Add the egg mixture, butter mixture and soda mixture and beat everything together until a soft dough forms.

Cover and refrigerate dough for at least 1 hour before handling.

Once dough is cold enough to work with; scoop out 1 teaspoon full of dough into each oreshki mold.

Lightly mold in the dough into the cookie iron.

Cover mold with the lid and bake in a preheated 375 degree F oven for 30-35 min or until golden.

Invert cookies onto a tray and continue to work with remaining dough chilling the dough in-between the handling. Cool cookies completely before filling.

TO ASSEMBLE ORESHKI: Fill each cookie half with the filling mixture and combine the cookie halves to form a walnut shape cookie.

Refrigerate shells and serve cold at all times. Enjoy!