Using a stand mixer or hand mixer, beat egg whites and salt on low speed until frothy. Gradually add castor sugar little by little. Beat on high speed until glossy and stiff peaks form. Add vanilla extract and beat just until well combined.

Sift in all-purpose flour into the egg white mixture. Add almond flour and fold with a spatula until well combined. Don't overmix. Add roasted whole almonds and dried cranberries and mix lightly to combine.

Transfer the batter into the prepared pan.

Bake for 25-30 minutes until golden brown. Remove from the pan and cool completely.

Cover with cling wrap and freeze for at least 2 hours or overnight until very firm.

Remove the cling wrap and transfer it to a cutting board. Slice thinly when still frozen by pressing a sharp knife straight down into 0.1-0.2 inch/3-5 mm thin slices.

Place the slices back on the baking sheets with the cut side up. Bake for 10 minutes, and then flip the cookies and bake for another 10 minutes or until just barely golden.

Place on a wire rack to cool completely.