In a small bowl, combine the warm milk with the active dry yeast and 1 teaspoon of sugar. Stir gently and let it sit for 5 to 10 minutes until frothy.

In a large mixing bowl, whisk together the all-purpose flour, buckwheat flour, remaining sugar, and salt.

Add the eggs and the activated yeast milk mixture to the dry ingredients. Stir until the batter is smooth and free of lumps.

Fold in 2 tablespoons of melted butter, blending well. Cover the bowl with a towel or plastic wrap and let the batter rest in a warm place for 30 to 60 minutes until it rises and becomes bubbly.

Heat a poffertjes pan over medium heat and brush each cavity generously with melted butter.

Using a small spoon or ladle, pour the batter into each cavity about three-quarters full.

Cook for about 1 to 2 minutes until bubbles form on the surface and the bottoms are golden brown.

Flip each poffertje with a skewer or fork and cook for another 1 to 2 minutes until golden and puffed.

Transfer to a warm plate and repeat with remaining batter, brushing the pan with butter as needed.

Dust the poffertjes liberally with powdered sugar and place a generous pat of butter on top while still warm.

Serve immediately, optionally with fresh fruit, syrup, or whipped cream for extra indulgence.