Preheat oven to 350 deg F and line two cookie trays/baking sheets with parchment paper or silicone mats and set aside.
In a bowl of stand mixer fitted with paddle attachment or using a hand mixer beat butter and sugar together on medium speed till the mixture gets very pale and fluffy. About 3-5 minutes.
Next add and mix in an egg, lemon zest, salt and vanilla too. Now with mixer on low speed, slowly add flour and mix only till flour disappears into the batter. Don't be alarmed if the dough looks crumbly at first, it will come together with ease in the next minute.
Now scoop dough into 1 tablespoon sized portions using a cookie scoop for uniform sized cookies and easy portioning. Roll these portions between your palms one by one and roll them into crack free balls.
Place the cookie balls on pre-lined cookie trays, about 2 inches apart. One cookie sheet will accommodate 12 cookies at ease.
Now gently create indentations in the cookie balls using a ½ teaspoon measuring spoon. If you notice there are cracks in the cookies at this point, smooth them out using your fingertips.
Pour preserves into the indentations and bake for 15-16 minutes or till their bottoms get slightly golden and the edges look set.
Remove from oven and allow to cool on the cookie tray for 5 minutes and then shift them to a wire rack to finish off cooling.
Sprinkle with confectioners' sugar and dig in! You can store them at room temperature for 3-4 days, covered tightly.