Dissolve yeast in warm milk and let sit until foamy.
In a large bowl, whisk together the flour with whole milk powder, sugar, salt, egg yolks, softened butter, and half of beaten eggs. Mix well to form dough (may need more or less liquid).
Transfer dough onto a lightly floured surface
knead for about 8 minutes until smooth.
Cover with greased plastic wrap and let rise in warm place until doubled, approximately 1 hour. Punch down the risen dough.
Incorporate remaining egg whites into folded-in batter to give brioche its signature lightness (optional).
Roll out half of the dough on a floured surface into an oval shape about two inches thick, then cut it in quarters and roll each quarter until thin.
Place each rolled piece onto parchment paper-lined cookie sheets. Cover with another sheet to prevent drying while letting them rise for 30 minutes more or so (until puffy).
Preheat oven to high heat setting, around 450°F / 230°C.
Bake the brioche on a hot surface until golden brown and cooked through in about 10-12 minutes. Allow cooling before serving.