Make a Cream: The Butter and Sugar – Using a stand mixer and paddle attachment, put butter and sugar in a big bowl and cream them together, beating it until light and fluffy. This makes sure the texture of your dough is tender and melt in your mouth.

Combine the Egg Yolk with Aromatics – Add in the vanilla extract, almond extract (only if you are using), and egg yolk. Again mix thoroughly, but this time ensure the mixture blends without any dry spots.

Blend in the Dry Ingredients – In a small bowl, combine flour and salt and whisk them together, then slowly add the mixture into the wet mixture while kneading and mixing on low speed as you go. If the dough has a crumbly texture to it, knead it gently and with some effort until smooth for the best results.

Put the dough on the Rolling Pin – Use a teaspoon or a small cookie scoop to portion out the dough first. For each portion, create a smooth ball and set them on a baking sheet lined with parchment paper. Set the portions about 2 inches apart for proper spacing.

Create the Indentation - Gently press down the thumb or back of a small spoon into the middle of the each dough ball. Crack some parts of the dough might begin to break so be careful. If this occurs, softly mold the edges together.

Turn your oven to preheat at 350 degrees Fahrenheit (175 degrees Celsius) while preparing your cookies.

Place ½ teaspoon of jam into each cavity of the cookies. Raspberry jam represents a timeless option yet substitute any jam or curd variety according to personal taste from lemon to chocolate.

Place the baking sheet inside the preheated oven where cookies should bake between 10-12 minutes or until the edges faintly brown.

Transfer cookies onto a wire rack using the baking sheet to rest for some time before full completion of cooling process.