Step 1Heat the oven to 350 degrees. Spread the almonds in a baking pan and toast until light brown, shaking the pan once or twice, about 15 minutes. Set aside.
Step 2Reduce the oven temperature to 300 degrees. Brush a 9x5-inch loaf pan with the melted butter and line with parchment paper.
Step 3Combine the dates, apricots, raisins, almonds and walnuts in a large bowl. Combine the cake meal, sugar and potato starch and mix well. Add the fruit mixture and mix evenly. Beat the eggs and vanilla to blend, then stir into the fruit mixture. Spoon the batter into the loaf pan and spread evenly, pressing the batter into the corners of the pan.
Step 4Bake the cake until golden brown, about 1 1/2 to 1 3/4 hours. Cool the cake in the pan on a rack for 10 minutes, then turn out of the pan. Peel off the paper and let cool on the rack.
Step 5Wrap in plastic wrap and foil. Refrigerate the cake at least 1 day or up to 2 months. To serve, place the cake on a wooden board and cut into thin slices with a serrated knife.