Preparation: Preheat the oven to 180°C. Ensure that a baking tray is adequately lined with a parchment sheet to facilitate the baking process.

Mixture Formation: Utilizing a stand mixer, cream the unsalted butter and sugar together until the consistency is smooth and the color turns pale. This should take approximately 3 to 4 minutes.

Incorporate Additional Ingredients: Proceed to add the egg yolk, lemon zest, lemon juice, and salt to the mixture. Beat these ingredients until they are thoroughly combined.

Flour Integration: While maintaining the mixer on a low setting, incrementally add the all-purpose flour. Continue to mix until moist clusters form. Avoid overmixing.

Dough Preparation: Manually gather the dough to form a cohesive ball. Handle the dough with care, ensuring not to overwork it.

Shaping the Cookies: Measure and take 1 tablespoon of the dough and form it into a ball with a diameter of approximately 1 inch. Place these balls on the prepared baking tray, ensuring they are spaced at least 1 inch apart to avoid merging during baking.

Creating an Indentation: With a floured finger or the back of a spoon, create a deep indentation in the center of each dough ball. The indentation should be deep enough to accommodate 1 teaspoon of lemon curd.

Initial Baking Phase: Place the tray in the preheated oven and bake the cookies until they become firm and the bottoms turn a light golden color. This should take between 18 to 20 minutes.

Adding Lemon Curd: Once removed from the oven and while the cookies are still hot, assess the depth of the indentations. If they appear shallow, re-establish the depth using a spoon. Subsequently, fill each indentation with lemon curd.

Secondary Baking Phase (Optional): If desired, return the cookies to the oven for an additional 2 minutes to set the lemon curd. Alternatively, one can proceed to the next step if the cookies are to be consumed immediately.

Final Presentation: Once fully cooled, dust the top of each cookie with a fine layer of icing sugar to enhance their visual appeal.

Alternative Variation: One may consider crafting Lemon Curd Tartelettes using a similar methodology.