In a large bowl, beat butter, cheeses, tarragon, oregano and garlic until well mixed. Beat in flour (the dough will be crumbly). Shape into a 14-in. roll. Wrap tightly and refrigerate for 4 hours or overnight.
Cut into 1/4-in. slices; place on ungreased baking sheets. Bake at 375° until golden brown and crisp, 10-12 minutes. Cool on wire racks.