In large mixing bowl, cream butter.

Once butter is creamed, slowly mix in sugar.

Continue beating, add in egg yolks (one at a time), cognac (if using), and vanilla.

Mix baking powder and flour together in separate bowl.

While mixing, slowly add flour to butter mixture. Continue mixing until soft dough is formed.

Take about 2 inch pieces and roll it out using your hands.

Form an upside down V, and braid pieces together. **

Place on baking sheet lined with parchment paper.

Repeat until all dough is used.

Create egg wash (egg and splash of water, mixed), and brush over each koulourakia.

Sprinkle with sesame seeds.

Place in preheated oven at 350F for 20 to 25 minutes, or until golden brown.

Remove, cool, and serve!