Sauté the butter and green onions until the moisture evaporates, then let cool (do not burn)
Combine all dry ingredients in a bowl and mix well (sift the flour)
Add egg, yogurt, and salt; use spatula to mix in green onions and cheese
Chill in refrigerator for 30 minutes at 2cm thickness
Divide into 3 portions
Bake at 160°C for 10 minutes, then at 150°C for 10 minutes (be careful not to burn)