Gather the ingredients. Allow the egg and butter to reach room temperature.
Combine the all-purpose flour, sugar, and baking soda in a bowl and set aside until later.

In the bowl of a stand mixer, add the butter, almond flour, and salt. Use the paddle attachment to cream these ingredients at medium speed for about 3 minutes.
You can also use a hand mixer for this step.

Since I halved the original recipe, I also used only half of one large egg. I cracked the egg into a small bowl, whisked it thoroughly, then measured the volume of the whisked egg using my measuring spoons. The total volume was about 4 Tablespoons of liquid. So, I transferred 2 Tablespoons to the dough and reserved the other 2 Tablespoons for brushing on top of the cookies for later.

Mix the egg into the dough at medium speed until just incorporated.

The dough will be fairly crumbly at this point. Use a spatula to scrape the bowl again and to finish mixing any dry pieces into the dough.

Transfer the dough onto a large sheet of plastic wrap and press it gently into a rectangle that is approximately 5 inches by 6 inches. Wrap the dough well and place it into the fridge to chill for at least 1 hour. Longer chilling is totally fine.

Line baking sheets with parchment paper. Preheat the oven to 325°F (163°C).

Cut the dough into approximately 30 balls. They'll be about 1 inch in diameter. I weighed mine to be more accurate and each weighed about 14 grams.

Place the dough balls onto the prepared sheets.

Use the heel of your hand to gently press the balls flat. You don't want to make them too thin. A little thicker than 1/4” (6 mm) is good.

Place a sliced almond on top of each cookie.

Bake the cookies for 13 to 16 minutes or until the cookies start to turn golden.

Let the cookies cool on the cookie sheets for about 5 minutes, then transfer them to wire racks to cool.