You will need:
-a bunch of black Lego bricks
-a bunch of white Lego bricks
-a baseplate, 48x48 studs
-the pattern seen below*
*I can't find where I got this pattern from so if anyone has the source let me know and I'll give credit.
Fill in the corners with black.
Add the smile, eyes, and nose.
Fill in the white and you're done. Happy Halloween!