Step 1

Using an electric mixer with a paddle attachment, beat butter, cream cheese, and granulated sugar until light and fluffy, about 3 minutes.

Step 2

Add vanilla and beat until mixed in.

Step 3

Add the salt to the flour and then add the flour to the butter mixture in 2 additions, stopping to scrape down the sides of bowl. Beat just until the flour is incorporated into the mixture.

Step 4

Place dough on a piece of plastic wrap, shape into a disk about 6 inches in diameter, wrap fully, and refrigerate for 1 to 24 hours.

Step 5

Place oven racks in upper-middle and lower-middle positions and heat oven to 350 degrees. Line 2 baking sheets with parchment paper.

Step 6

Break 5 of the chocolate bars apart at the seams so you have a total of 20 pieces.

Step 7

Roll dough on a lightly floured surface into a 20 by 8-inch rectangle. Cut dough into twenty 2 by 4-inch rectangles.

Step 8

Place a piece of chocolate crosswise across each piece of dough. Chocolate should overhang the edges some. Fold dough around chocolate and place on prepared baking sheets seam side down.

Step 9

Brush tops with egg and sprinkle with sugar.

Step 10

Bake for 18 to 20 minutes, until golden brown, switching and rotating baking sheets halfway through. Let cookies cool 5 minutes and then remove to wire racks to cool completely.

Step 11

Break remaining chocolate bar into pieces, place in a microwave-safe bowl, and microwave on 50% power for about 1 minute. Stir and drizzle on cookies.