In a large bowl, cream the softened butter and sugar together using an electric mixer until the mixture is pale, light, and fluffy, which usually takes about 3 minutes.

Add the egg and vanilla extract to the butter mixture, beating on medium speed until fully incorporated.

In a separate medium bowl, whisk together the flour, ground cardamom, poppy seeds, and sea salt to ensure the spices are evenly distributed.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined and a soft dough forms.

Scoop rounded tablespoons of dough, about 30 grams each, and roll them into balls using your palms.

Place the balls on the prepared baking trays, spacing them about 5 centimeters apart to allow for slight spreading.

Use the bottom of a glass to gently flatten each ball into a disc about 1 centimeter thick.

Bake for 10 to 12 minutes, or until the edges are just barely turning a light golden brown.

Remove the trays from the oven and let the cookies rest on the hot tray for 5 minutes before transferring them to a wire rack to cool completely.