Preheat your oven to 375˚F / 190˚C. To the bowl of a food processor, add the cheeses, kosher salt, oregano, red pepper flakes, flour, butter, and sun dried tomatoes. Pulse until the butter is broken down into lentil-sized pieces.
Add in the milk and pulse until incorporated. The dough should stick together when pressed between your fingers. Then turn the dough out onto a lightly floured work surface and knead briefly until you can form a solid block of dough.
Lightly flour a work surface and roll out the dough on top of it until you achieve a roughly 20"x15" (50x40-cm) rectangle.
Using a knife or fluted pastry cutter, cut the sheet of dough into ¾" rectangles. Use a wood skewer or toothpick to dock a hole into the center of each cracker, then sprinkle with kosher salt.
Move to a parchment-lined sheet pan and bake at for about 12 minutes, until the bottoms of the crackers are golden brown. Move to a wire baking rack and let them cool completely before enjoying.
