This is an instant drink, so the basic preparation is simple: put the powder in a cup, add hot water, and stir until fully mixed. Because the powder contains oat flakes and pine nut flour, it does not dissolve like sugar; instead, it forms a suspension with some body. A spoon or small whisk helps get an even texture without lumps.
For a creamier and milder version, prepare it with a fermented milk product such as kefir or yogurt. This makes the drink thicker and gives it a slightly tangy taste. If you go this route, avoid adding the powder to boiling liquid. High heat can curdle the fermented milk; a warm or room-temperature product works better and is enough to blend the powder.
Start with a small amount of powder and adjust to your taste. The drink becomes richer and more chocolatey with more powder, and lighter with more liquid. You can also mix the powder with a small amount of hot water first to make a paste, then top up with the liquid of your choice. This is a practical trick for reducing clumps.
When you are at work or travelling, the water version is the most practical: all you need is a cup, hot water, and a spoon. The fermented milk version is better suited to home use, as it turns the product into a more substantial drink.