Burn Pi into a Pie for Pi Day! Alternatively cut out a stencil to powder sugar top Pi onto a Pie.Option 2 is probably better at avoiding burnt pie flavor.
For my laser I burned at about 13W power and 120mm/s speed. I went back and vector etched the lettering at 13W power and 20mm/s speed to sharpen the edges.
For the stencil use whatever material you have around at the appropriate power/speed you typically use for it. Card stock would work just as well as acrylic or just about anything else.