Soft Double-Berry Bars

In a small saucepan, combine preserves and fruit spread. Bring to a gentle boil over medium heat; reduce heat to low, and simmer, stirring frequently, until thickened and reduced to just over 1 cup (340 grams), 13 to 16 minutes. Remove from heat, and let cool completely.

In the bowl of a stand mixer fitted with the paddle attachment, beat butter, brown sugar, and orange zest at medium speed until pale and creamy, 2 to 3 minutes, stopping to scrape sides of bowl. Beat in egg and vanilla, stopping to scrape sides of bowl.

In a medium bowl, whisk together flour, salt, cinnamon, baking powder, and baking soda.

Add orange juice to butter mixture, and beat at low speed. With mixer on low speed, gradually add flour mixture, beating until just combined. Turn out dough onto a sheet of plastic wrap, and flatten into a disk. Wrap in plastic wrap, and refrigerate until firm, about 1 hour.

Preheat oven to 350°F (180°C). Line rimmed baking sheets with parchment paper.

Turn out dough onto a lightly floured surface, and roll into a 13½-inch square. Cut into 4 strips (about 3¼ inches wide each).

Gently stir cooled fruit mixture until smooth (it will be thick); spoon into a pastry bag, and cut a ½-inch opening in tip. Pipe a 1-inch strip of filling (about 1⁄4 cup or 80 grams each) down center of each dough strip, leaving a 1⁄2-inch border on short sides. Working with 1 dough strip at a time, brush off any excess flour with a pastry brush; fold sides of dough strip over filling, gently pressing seam to seal and making sure there are no gaps between dough and filling. Place dough logs, seam side down, on prepared pans. Lightly spray logs with water, and sprinkle with demerara sugar.

Bake until edges are light golden brown, 18 to 20 minutes. Using a bench scraper, immediately cut each log into 1½-inch pieces, wiping scraper between each cut. Let cool on pans, touching for 10 minutes. Remove from pans, and let cool completely on a wire rack. Store in an airtight container for up to 1 week.