Using a stand mixer fitted with the paddle attachment, or an electric hand mixer, beat the softened butter, dark brown sugar, egg yolks, heavy cream, vanilla, and grated lemon peel together until noticeably lighter in color and fluffy in texture. Continue mixing for approximately 5–6 minutes.

Add the almond flour and beat again until it is evenly incorporated throughout the mixture.

In a separate mixing bowl, thoroughly blend the sifted regular flour with the baker’s ammonia, salt, cinnamon, ginger, nutmeg, cloves, cardamom, and ground anise seed.

With the mixer still running, gradually incorporate the dry mixture into the wet ingredients until a cohesive dough forms.

When preparing the dough without a stand mixer, begin by stirring it with a wooden spoon. Once the mixture becomes too firm to stir comfortably, continue combining it by kneading with your hands as necessary.

If the finished dough appears excessively dry or crumbly, work in a small amount of additional egg yolk until the proper consistency is achieved.

Place the wrapped dough in a cool location for a minimum of 5 hours, or leave it to rest overnight. Do not refrigerate the dough during this initial resting period, since refrigeration can make it brittle.

Allowing the dough this extended resting time helps the spices develop and contributes to the desired final texture.

Dust a work surface lightly with flour, then roll the rested dough to approximately 4 mm thick, or slightly less than 1/4 inch.

Cut it into small rectangular cookies reminiscent of Biscoff biscuits, or shape the dough with decorative molds, cookie stamps, a patterned rolling pin, or cookie cutters.

When using cookie molds, coat them lightly with flour before pressing in the dough to reduce sticking.

Arrange the shaped cookies on a non-stick baking sheet. Transfer the tray to the refrigerator and chill the cookies for at least 1 hour before baking.

Preheat the oven to 375°F (190°C).

Position the baking sheet on the center oven rack and bake the cookies for 10–12 minutes, or until they develop a well-browned, caramelized appearance.

Leave the baked cookies on the baking sheet for several minutes before carefully transferring them to a wire cooling rack. Allow them to cool completely.

Once fully cooled, place the speculoos in an airtight container and store them in a cool location.

For the most developed spice flavor, allow the baked cookies to mature for at least one week before serving. Properly stored speculoos will remain suitable for several weeks.