Using a food processor with a blade (chopper) attachment, pulse the cheeses, flour, and onion powder together 4 pulses.
Cut butter into ¼ inch pieces and add to mixture.
Pulse until mix is crumbly.
Slowly add water 1 tbsp at a time and pulse until mixture is "mealy".
Transfer to a bowl and cover, then refrigerate for at least an hour.
Remove and dump mixture onto table and form ball with dough.
Place ball of dough between 2 pieces of parchment paper and roll out with rolling-pin to ? thick.
The thinner the dough the better.
Preheat oven to 375 degrees.
Using a pizza cutter, cut dough into 1 inch x ½ inch pieces.
With a chop stick of skewer, poke 2 holes into each cracker.
Continue until all crackers have been made.
Transfer to baking sheet and sprinkle with salt.
Bake in oven for 14-17 minutes until crackers are slightly brown.
Remove from oven and allow to cool