In a large bowl, using a standing mixer with a whisk attachment or a hand held mixer, mix the eggs and sugar until pale yellow and fluffy, at least 5 minutes.

Add the melted butter, mayonnaise, sour cream until evenly mixed. Add the baking soda dissolved in vinegar and mix again until combined.

Add the flour and mix, starting on low speed and gradually increasing the speed to medium, until all the flour is incorporated.

Shape little balls from the prepared cookie batter, about 3/4 of a teaspoon of batter for each walnut shape. It's very helpful to shape a lot of the cookie balls before you start cooking them.

When you have a lot, or even all of the cookie balls shaped, (cover them with plastic wrap so they don't dry out), heat the oreshki griddle on medium heat until hot.

Quickly place a cookie ball into each of the cookie wells, close the lid and tightly hold the two ends, squeezing them as tight as you can. Cook each side until golden on both sides, flipping the griddle over halfway through. The time really depends on the type of griddle you are using and on your stove. I cooked mine for only 1 - 1 1/2 minutes per side, but you might need to cook them longer, up to 3 minutes per side.

The cookie batter will spread when you're squeezing the two sides together and that's a good thing, since it makes sure that the entire walnut shape is completely covered and you will also use all the leftover cookie scraps in the filling.

Use a small and sharp paring knife to cut each of the walnut shaped cookies out, setting aside all the scraps. Crush all the cookie scraps into small crumbs, using a ziplock bag and a rolling pin, or a food processor. Cook all of the cookies, cutting them out into walnut shapes.

For the filling, in a large bowl, using a standing mixer or a hand held mixer, combine the dulce de leche, butter, cream cheese and vanilla extract until evenly combined. Add the cookie crumbs to the filling and mix again to combine. Instead of the crumbs, you can use crushed nuts, but I prefer the taste and texture of the cookie crumbs.