Preheat the oven to 350°F and line 2 baking sheets with parchment paper. Let the butter soften fully so it creams smoothly, which helps the dough press evenly.
In a large mixing bowl, beat the softened butter and powdered sugar with an electric mixer for 2 to 3 minutes until light, smooth, and fluffy. Mix in the vanilla extract, almond extract, and milk until fully combined.
In a separate bowl, whisk together the all-purpose flour, cornstarch, and salt. Add the dry ingredients to the butter mixture in 2 additions, mixing on low speed just until a soft dough forms with no dry pockets.
Transfer the dough to a cookie press fitted with a seasonal disc. Press the cookies directly onto the prepared baking sheets, spacing them about 2.5 cm apart. If desired, decorate the tops with sanding sugar or holiday sprinkles.
Chill the shaped cookies on the baking sheets for 15 minutes so they hold their details well during baking. This short rest also helps prevent spreading.
Bake 1 sheet at a time for 10 to 12 minutes, or until the bottoms and edges are just lightly golden. Avoid overbaking so the cookies stay tender rather than dry.
Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely before serving or storing.
Repeat with the remaining dough, keeping any unpressed dough at cool room temperature so it stays soft enough for the cookie press.