Heat the water in a small saucepan, add the butter and stir until it melts completely. When the water and butter mixture comes to a gentle boil, add the salt, then sprinkle in the flour all at once while stirring constantly with a spatula or wooden spoon. Keep mixing until a smooth dough forms that pulls away from the sides of the pan and gathers into a ball. Remove the pan from the heat and let the dough cool down until just warm to the touch.
When the dough is lukewarm, add the eggs one at a time, mixing well after each addition until fully incorporated. You should get a glossy, smooth dough that falls slowly and heavily from the spoon. Dip a spoon in cold water, scoop portions of dough and place them on a baking sheet lined with parchment paper, leaving enough space between them because they will puff up a lot in the oven.
Preheat the oven well, then place the tray inside and bake the éclairs for about 15 minutes without opening the oven door, until they are puffed and nicely golden. Turn off the oven, but leave the tray inside for a few more minutes with the door slightly ajar so they cool gradually and the shells do not collapse. Once the oven has cooled down, remove the éclairs and let them cool completely on a rack.
In a mixing bowl, combine the farmer’s cheese (or well‑drained cottage cheese), vanilla, sweetened condensed milk and cocoa powder. Beat with a mixer or rub with a spatula until you get a smooth, creamy filling with no lumps. If needed, adjust the consistency with a little extra condensed milk for a softer cream or more cheese for a firmer texture, depending on your preference.
Using a small serrated or table knife, cut each éclair lengthwise on the side to create a pocket, without splitting it all the way through. Spoon or pipe the prepared cream inside each shell, filling it generously, then arrange the filled éclairs neatly on a serving platter.
In a small saucepan, melt the butter over low heat, then add the milk, sugar and cocoa powder. Stir well and bring the mixture to a brief simmer for about 1 minute, until the sugar dissolves and the glaze becomes smooth and glossy. Remove from the heat and let it cool slightly so it thickens just a bit before using.
Drizzle or spoon the glaze over each filled éclair, coating the top generously. Place the platter in the refrigerator for the glaze to set, then serve the éclairs chilled, with the velvety cottage cheese cream inside and the shiny chocolate glaze on top.