01 -
Toss flour, cornstarch, baking powder, lemon zest, and powdered sugar into a big bowl and mix it up with a whisk.
02 -
Pour vanilla, softened butter, and the egg in with the dry mix. Start on low speed, then make it faster till it all forms a dough.
03 -
Wrap the dough tightly in some plastic wrap, then stick it in the fridge for about an hour.
04 -
Flatten the dough to under 1/4 inch thick, then use a round cutter (about 2 1/2 inches) to slice out circles.
05 -
Put a little bit of jam right in the middle of each circle. Pinch the sides so the ends stay open.
06 -
Line a baking tray and bake at 350°F for about 12 to 14 minutes, till the cookie bottoms get a nice golden color.
07 -
Let cookies cool on a rack, then sprinkle a little powdered sugar on top.