Beat the eggs with the sugar, add the honey and oil, then the baking soda and cinnamon, finally pour in flour gradually until the mixture becomes a dough. From the resulting dough, shape small balls of roughly the same size.
Cover the baking tray you intend to use with baking paper and arrange the balls in it with some distance in between them. Bake in a preheated 356°F (180 °C) oven about 20 min. Take them out and while still warm, begin to scoop them out from the flat side.
Place the crumbs you scoop out in a bowl (you're going to need them for the filling). After scooping out all of them, start making the filling.
To the bowl of crumbs, add the melted butter, milk and ground walnuts. Stir until you get a homogeneous mixture and begin filling up the holes and sticking them together in pairs.
From the ingredients listed you'll get about 40 halves or 20 gingerbread cookies. Once you've stuck them together, leave them to soften for 5-6 hours.