Butter the cake pan, line the base with waxed or parchment paper, and then butter and flour it. Wash the raspberries, dry them on paper towels, and then snip off the blossom ends and stems. Sift together the flour, baking powder and salt. Heat the oven to 350 degrees. Cream the butter until smooth in an electric mixer. Add the sugar and continue to beat until soft and light, 2 to 3 minutes. Beat in the egg until well mixed, about 1 minute. Stir in the ground almonds by hand, followed by the flour mixture. Expect the batter to be quite stiff. Spread half the batter in the cake pan. Sprinkle the fruit on top and dot with the remaining batter so the fruit is almost covered. Bake until the torte starts to shrink from the sides of the pan and the top is firm when lightly pressed with a fingertip, 45 to 55 minutes. The top will be rustic looking, like a crumble. Let the torte cool for 10 to 15 minutes in the pan, then loosen the sides and slide the torte onto a rack to cool completely. Sprinkle it with confectioners' sugar and serve it warm or at room temperature.