In large mixing bowl beat butter until light and fluffy. Add the sugar and beat for 10 minutes on medium speed. Add four of the eggs, one at a time, and beat well after each addition. Beat in the vanilla.
Combine the flour, baking powder and salt in a separate bowl. Add to the butter mixture and stir to form soft, cohesive dough. Add flour if dough is too soft to handle easily.
Preheat oven to 180 degrees C. Grease baking trays.
Lightly flour a work surface. Break off 3cm lumps of dough and roll on floured surface into ropes about 20cm long and 5mm in diameter. Cross the ends and twirl dough in a loop in the opposite direction, forming a braid. Place on baking trays about 3cm apart.
Beat remaining egg. Brush onto braids for glaze and sprinkle with sesame seeds. Bake 20 to 25 minutes. Let cool on baking trays for 10 minutes then remove to racks to cool completely.