Preheat the oven to 400F. In a large mixing bowl beat together 1 egg, 5 egg yolks, 1/2 cup sugar, and the rum or lemon zest until very thick. Beat in the flour. In a separate bowl beat the egg whites with an electric mixer until stiff peaks form. Beat in the remaining 1/2 cup sugar, 1 tablespoon at a time. Fold the egg whites into the flour mixture and stir in the melted butter. Grease the springform pan and line the base with a round of wax or parchment paper. Pour the batter into the pan and place in the oven. After 10 minutes, lower the temperature to 300F. Bake for 15-20 minutes more, until golden, and a cake tester comes out clean. For the praline topping, mix together the sliced almonds, sugar, and beaten egg in a small bowl and spread mixture on top of the cake. Sprinkle with the confectioner╒s sugar. Bake for 5-10 minutes longer, until the praline is golden. Cool on a wire rack.
