Preheat oven to 350°F (180°C). Lightly spray a 13×9-inch baking pan with cooking spray; line pan with foil, letting excess extend over sides of pan. Lightly spray foil.

In a large bowl, place cake crumbs; pour tea over crumbs, making sure they are well coated and slightly submerged. Set aside to soak.

Let Shortcrust Pastry stand at room temperature until softened, 10 to 15 minutes. On a lightly floured surface, roll one half into a 13×9-inch rectangle, lightly flouring dough and work surface as needed. Place in bottom of prepared pan, pressing into an even layer.

In a medium bowl, whisk together flour, baking powder, and salt. Stir in brown sugar; using your fingers, rub butter into flour mixture until well combined. (Mixture should resemble wet sand.) Stir in cinnamon, ginger, nutmeg, and cloves until well combined.

Strain cake crumbs through a fine-mesh sieve, gently pressing on crumbs to release as much liquid as possible. Transfer cake crumbs to a large bowl. Add milk, 2 eggs (100 grams), and lemon zest, whisking to combine. Stir in flour mixture, raisins, and figs until well combined; pour into prepared pan, and using a small offset spatula, spread into an even layer.

On a lightly floured surface, roll remaining Shortcrust Pastry into a 13×9-inch rectangle, lightly flouring dough and work surface as needed. Place on top of cake crumbs mixture; using a small sharp knife, trim any uneven edges, if desired, and cut a few diagonal slashes across top.

In a small bowl, whisk remaining 1 egg (50 grams); brush onto pastry.

Bake until pastry is golden brown and filling can be heard bubbling, 55 minutes to 1 hour. Let cool completely in pan on a wire rack. Using excess foil as handles, remove from pan. Using a serrated knife, cut into bars. Before serving, garnish with confectioners’ sugar, if desired.