Put eggs, essences and castor sugar in a mixing bowl. Beat until mixture turns fluffy.
Gradually add sifted dry ingredients and mix in ground almonds. Stir in whole almonds and almond flakes. Combine until mixture turns into a sticky dough.
Divide the dough into two portions. Lightly dust your hands with flour and form the portions into two long rolls. Place the rolls on a lightly greased tray and bake in a preheated oven at 180°C for about 30-35 minutes or until lightly golden brown. Place the baked rolls on a wire rack to cool.
Using a serrated knife, cut the rolls crosswise into very thin slices. Arrange the slices on a baking tray and bake again in a preheated oven at 160°C for about 20-25 minutes or until completely dry and crispy. Halfway through baking, turn over the biscotti slices to ensure an evenness in the browning process. Transfer the biscotti to a wire rack to cool completely.