Heat oven to 350°F. Line two baking sheets with parchment.
Cream butter and sugar in a bowl until pale and fluffy, 2–3 minutes.
Beat in the beaten egg, almond extract, and vanilla until smooth.
Whisk all-purpose flour, almond flour, baking powder, and salt in a separate bowl.
Add dry ingredients to the creamed mixture. Mix on low just until a soft dough forms.
Scoop dough by rounded tablespoons, roll into balls, and set 2 inches apart on sheets.
Gently flatten each ball. Press a few sliced almonds on top and sprinkle turbinado sugar if using.
Bake 12–14 minutes, until edges turn light golden and centers look set.
Cool 5 minutes on the sheet, then transfer to a rack to finish cooling.