Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together the butter and sugar until light and fluffy. Add in the egg yolk, milk, and almond extract, mixing well. Gradually incorporate the flour, blending until the dough becomes thick and slightly chunky. Cover the bowl and place in the refrigerator to chill.

While the dough is chilling, prepare the filling. Combine the almond paste, sugar, milk, egg yolk, and almond extract in a separate bowl. Beat until all ingredients are fully incorporated and the mixture is smooth.

Using a medium cookie scoop, form balls of the chilled cookie dough. Flatten each ball gently in the palm of your hand. Take a scant tablespoon (or about 0.5 oz) of the almond filling, roll it into a small ball, and position it in the center of the flattened dough. Carefully wrap the dough around the filling, rolling it between your hands to create a smooth, uniform ball. Place each ball on a parchment-lined baking sheet. Flatten slightly with your hand, and if desired, use a round cookie cutter to tidy the edges. Repeat this process with the remaining dough and filling.

Bake in the preheated oven for 15-20 minutes, keeping a close eye on the cookies to ensure they do not overbrown.

Allow the cookies to cool on the baking sheet. Once cooled, dust with powdered sugar. Serve and enjoy.