Butter Block

1. Combine butter and flour in bowl of a mixer fitted with a paddle attachment and beat on medium speed for 2 minutes.  Scrape sides of bowl; beat one minute more.  Cover with plastic wrap.  Set aside.

Dough

1. Combine yeast and milk in the bowl of a mixer fitted with paddle attachment and mix on low speed. Slowly add sugar, orange zest, cardamom, vanilla and eggs. Mix well.
2. Change from paddle to dough hook and add salt and flour, a little at a time, increasing speed to medium as flour is incorporated. Knead dough for 5-6 minutes, until smooth. If dough seems sticky, add a bit more flour.
3. Transfer dough to a lightly floured baking sheet and cover with plastic wrap. Refrigerate for 30 minutes.
4. After dough has chilled, turn it out onto a lightly floured surface. Roll dough into a rectangle approximately 18 x 13 inches and 1/4 inch thick. If dough is sticky, dust it lightly with flour as needed. Spread butter block evenly over center and right thirds of dough. Fold left edge to right, covering half of  butter block. Fold right third of rectangle over center third. This is called a “turn.” Mark dough by poking it with your finger to keep track of your turns. Place dough on a baking sheet, wrap it in plastic wrap, and refrigerate for 30 minutes.
5. Place dough lengthwise on floured work surface. The open ends should be to your right and left. Roll dough into another approximately 13 x 18 inches, 1/4 inch thick rectangle. Again, fold left third of  rectangle over center third and right third over center third. This completes turn two. Refrigerate  dough for 30 minutes. Repeat this process 2 additional times, refrigerating after each turn.  Refrigerate at least 4 hours after fourth and final turn.

Making Braid

1. Line a baking sheet with a silicone mat or parchment paper. Divide refrigerated dough into two pieces.  Work with one piece at a time.
2. Place a large piece of parchment onto work surface and dust with flour.  Place one dough half onto  parchment and roll into a rectangle roughly 10 x 15 inches.
3. Along one long side of pastry make parallel, 4 inch long cuts with a knife, each about 1 inch apart. Repeat on the opposite side, making sure to line up cuts with those on other side.
4. Spoon your preferred filling down center of rectangle. Starting with top and bottom “flaps”, fold  top flap down over filling to cover. Next, fold bottom “flap” up to cover filling. Now begin folding cut side strips of dough over filling, alternating first left, then right, until finished.  Tuck in ends.

Proofing and Baking

1. Proof prepared braid until double in size, roughly 1-2 hours.  Near end of proofing, preheat oven to 400°F. Brush braid with egg white wash and sprinkle with sugar, if desired.
2. Bake for 10 minutes, then rotate pan and reduce temperature to 350°F.  Continue to bake until golden brown, roughly 15 to 20 minutes more. Allow to cool on pan.  Serve warm.