In the bowl of a stand mixer, mix sugar, eggs, and vanilla on low speed until smooth. Mix in flour, baking powder, and salt on low speed until just combined, then stream in oil until dough comes together. Mix in your chosen flavor additions (see list below).

Shape dough into a disk and wrap in plastic wrap. Chill for a minimum of one hour.

Preheat oven to 350 degrees Fahrenheit. Prepare two sheet pans with Gefen Parchment Paper.

Remove dough from the fridge and cut into four pieces so it’s easier to work with. Lightly flour a sheet of parchment paper, place one piece of dough on top, and lightly flour the dough. Place another sheet of parchment paper on top and gently roll dough as thin as possible.

Remove the top parchment paper, cut into triangles, and place on the sheet pans. Cut out smaller triangles from the middle of half the cookies. Repeat with the remaining pieces of dough. Bake for eight to 10 minutes until just barely golden on the edges. Let cool on the pans for 10 minutes, then transfer to a cooling rack to cool completely.

Fill with your choice of filling (see below) and sandwich the cookies together with the cutout cookies on top so the filling shows through. Decorate with melted chocolate, powdered sugar, or whatever you like.