Preheat oven to 350°F (175°C).

Sift together flour, cardamom, baking powder, salt, and baking soda in a bowl.

In a separate bowl, cream together the butter, sugar, and almond extract using an electric mixer until light and fluffy.

Beat in the eggs one at a time, mixing well after each addition.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined.

Stir in the slivered almonds.

Divide the dough into 4 equal portions and shape each portion into a log, approximately 11 inches long and 2 inches wide.

Place the logs on an ungreased baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 20 minutes, or until the logs are pale golden brown.

Remove the baking sheet from the oven and let the logs cool on the sheet for 5 minutes.

Transfer the logs to a cutting board and use a serrated knife to slice them diagonally into 1/2-inch thick slices.

Reduce the oven temperature to 300°F (150°C).

Arrange the rusk slices, cut side down, on baking sheets.

Bake in the preheated oven for another 18 minutes, or until golden brown.

Remove the rusks from the oven and transfer them to a wire rack to cool completely.