Preheat oven to 350 F.
In a large bowl, whisk together eggs, yogurt and mustard. Stir in chard, onions and salt and pepper.
Mix melted butter with oil and using a pastry brush, brush bottom and sides of a 9 inch springform pan.
Working quickly to avoid phyllo from drying out, using a pastry brush, brush each sheet of phyllo with butter mixture. Layer them on top of each other in pan with edges of phyllo draping over sides of pan
Fill with egg mixture and tuck in edges just over the pan rim. if you have any butter mixture left, gently brush phyllo tops.
Sprinkle halloumi cheese evenly on top of egg mixture. Lay garlic flat scapes evenly on top of halloumi.
Bake for 20-25 minutes or until phyllo is dark golden in colour. Gently cover top with foil and bake for an additional 40-45 minutes or until egg has set. Depending on your oven, time will vary for the egg to set. Its important to cover the phyllo pie to avoid phyllo from burning.
Allow to sit for 5 minutes prior to removing from spring form pan. Serve hot.