Combine blueberries, raisins, brown sugar, orange zest, and juice in a medium saucepan and bring to a boil. Simmer, uncovered, for 15 minutes or until nearly all of the liquid has evaporated, stirring occasionally. Remove from heat; let cool. Scrape mixture into a food processor and purée until smooth.

Heat oven to 350°F. Combine butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and beat until fluffy, about 5 minutes. Beat in eggs, one at a time, then add vanilla. Stir together all the dry ingredients in a separate bowl then add to the butter mixture and beat on low until flour is completely incorporated.

Divide dough into 4 equal pieces. Wrap 3 in plastic wrap and refrigerate while you roll out the other piece. Place 1 piece of dough between 2 pieces of parchment or waxed paper and roll into a 12in-x-5in rectangle, about 1/4in thick. (The easiest way to do this is to roll it out lengthwise to 12 inches first, then  out). If you are feeling anal you can trim the edges, if not, leave them rough. Remove the top piece of parchment and spread about 1/4 cup of the blueberry filling down the middle. Use the bottom piece of parchment to fold the dough lengthwise over the filling and seal the edges with the tines of a fork.

Cut crosswise into 8 slices. Place 2 inches apart on a parchment or silpat lined baking sheet and repeat with another piece of dough. When one baking sheet is filled bake for 15 minutes, or until browned. Remove to a rack to cool and repeat with remaining dough.