On a lightly floured work surface, roll out 1 piece of dough to 1/8 inch thick. Gently press into a 4-by-14-inch fluted, rectangular tart pan with a removable bottom. Trim dough flush with top edge of pan. Prick bottom of dough all over with a fork. Refrigerate until cold, about 1 hour. Repeat with remaining dough.
Preheat oven to 375 degrees. Line each chilled tart shell with parchment paper, and fill with pie weights or dried beans. Bake until just starting to color, about 20 minutes. Remove parchment and weights. Return to oven, and bake until bottom of tart is golden, about 5 minutes. Cover edges with foil to prevent burning, and bake until crisp and dark golden brown, about 12 minutes more. Transfer to a wire rack; let cool completely. Carefully remove tart shells from pans.
Melt chocolate in a heatproof bowl set over a pan of simmering water, stirring until smooth. Using the back of a spoon, spread half of the melted chocolate onto bottom of each tart shell, and refrigerate until chocolate is set, about 10 minutes.
Using the back of a spoon, spread half of the creme fraiche filling over each chocolate layer; set aside.
Heat each jam in a separate small saucepan over low heat, stirring occasionally, until liquefied and smooth. Strain each through a fine sieve into a small bowl. Let cool slightly. Toss blueberries with the apricot jam to coat; set raspberry jam aside.
Make the first tart: Arrange 3 rows of raspberries 2/3 the length of the tart shell, leaving space between each row (you should have 4 empty rows). Dust raspberries and edges of tart shell with confectioners' sugar until coated white. Fill empty third with 2 layers of glazed blueberries, arranging them snugly in rows to cover the filling completely. Fill empty rows with raspberries, and carefully brush these raspberries with reserved raspberry jam.
Make the second tart: Repeat process with raspberries only, alternating 3 full-length rows of sugar-dusted berries with 3 full-length rows of glazed berries.
Arrange tarts on a serving tray or board, and serve immediately.