Method
Preheat the oven to 350 degrees F (175 degrees C). Grease two cookie sheets.
Combine flour, baking powder, and salt in a bowl.
Beat butter in a large bowl with an electric mixer until light and fluffy. Add sugar and beat on medium speed for 10 minutes. Add 4 eggs, one at a time, beating well after each addition. Beat in vanilla. Gradually beat in flour mixture until a soft, cohesive dough forms; add more flour if dough is too soft to handle easily.
Break off 1-inch lumps of dough and roll on a floured surface into 1/4-inch-thick ropes, about 7 inches long. Cross the ends and twirl dough in a loop in the opposite direction, forming a braid. Transfer braids to the prepared cookie sheets, placing them 1 inch apart.
Beat remaining egg in a small bowl. Brush onto braids for glaze and sprinkle with sesame seeds.
Bake in the preheated oven for 20 to 25 minutes. Let cool on the sheets for 10 minutes, then remove to wire racks to cool completely.