6 ounces unsweetened chocolate, chopped
½ cup dairy-free, soy-free vegetable shortening
2 cups granulated sugar
2 jars (4-6 ounces each) prune puree or apple-plum puree (baby food)
1 tablespoon pure vanilla extract
1¾ cups plus 2 tablespoons Basic Gluten-Free Flour Mix, plus a bit more for preparing baking pan
½ teaspoon xanthan gum
1 tablespoon baking powder
1½ cups dairy-free, soy-free chocolate chips
Center a rack in the oven. Heat the oven to 325 degrees. Grease a 9-by-9-inch pan, then sprinkle with a little gluten-free flour mix, tapping out any extra.
Combine the unsweetened chocolate and shortening in a microwave-safe bowl, and melt in the microwave, checking every 30 seconds until melted. Stir in the sugar and the puree. Mix well, add the vanilla, and beat until smooth.
Whisk together the flour mix, xanthan gum and baking powder. Add to the chocolate mixture in three batches, stirring well after each addition. Beat until smooth. Fold in the chocolate chips.
Spread the batter evenly in the prepared pan. Bake for 55 minutes, rotating the pan halfway through, until glossy and just beginning to pull away from the sides.
Let cool completely, then cut into squares. Store in an airtight container.
"The Allergen-Free Baker's Handbook" by Cybele Pascal (2009 Celestial Arts)