Preheat the oven to 375 degrees . Grease a 9-inch springform pan, line with parchment paper, grease the paper, then flour the pan. In a medium bowl, whisk together the flour, baking powder and salt.
In a large bowl, whisk together 3/4 cup granulated sugar and the 2 eggs until pale yellow, 1 to 2 minutes; whisk in the butter. Stir into the flour mixture until just combined. Pour half of the batter into the prepared pan and top with half of the pear slices and half of the chocolate; repeat with the remaining batter, pears and chocolate.
Using a food processor, finely grind 1/4 cup almonds with the remaining 1/4 cup granulated sugar. Add the egg white and process until smooth. Drizzle over the cake and sprinkle with the remaining 1/4 cup almonds. Bake until a toothpick inserted into the center comes out clean, 45 to 50 minutes. Let cool slightly, then dust with the confectioners' sugar.