Preheat oven to 150ºC . In medium bowl, combine flour, almonds, baking powder, salt and cinnamon and wire whisk. in large bowl with an electric mixer cream butter and sugar. Add egg yolks, the vanilla and almonds extracts, and beat at medium heat until light and fluffy. Add the flour mixture and blend at low speed until just combined. Do not overmix. Roll dough into 4 cm balls. Place 5 cm apart on ungreased baking sheet. With index fingers press an indentation in centre of each ball to hold filling. Bake 22-24 minutes or just until golden brown on bottom. Transfer cookies to cool, flat surface with spatula. In a small bowl combine jam and grated lemon peel. Place half teaspoon of filling mixing in centre of each cooled cookie. If you wish to add an extra decorative touch, sift confectioner's sugar over cookies and place sliced almonds in the jam filling.