There are many requests for Minecraft cakes.  But I'm not sure how to create crisp block letters that look pixelated with buttercream.  Any suggestions?

I would do a transfer. This isn't my cake but if you look closely at the name, the font is done with a BC transfer in the Minecraft logo. 

http://jenniferstonebarger.blogspot.com/2013/11/minecraft-cake.html?m=1