Give the Roasted Buckwheat Groats a quick rinse in a fine-mesh sieve and drain well; this removes any dust and wakes up the nutty aroma.
Place the drained groats in a medium saucepan and, if you like a deeper toasted flavor, briefly toast them over medium heat for 1–2 minutes until fragrant.
Add the Milk to the saucepan with the groats and stir to combine. Use roughly twice the volume of milk to groats (adjust for desired thickness).
Season with a small pinch of Salt, bring the mixture to a gentle boil, then reduce the heat to low, cover, and simmer until the groats are tender and most of the liquid is absorbed, about 10–15 minutes. Stir occasionally to prevent sticking and add a splash more milk or water if it becomes too dry.
When the kasha is soft and creamy, remove from the heat and stir in the Butter until melted and fully incorporated.
Sweeten to taste with Sugar and give a final stir. Serve hot, with an extra pat of butter or a drizzle of milk if desired.
