In a small bowl, combine the poppy seeds and milk. Set aside.
In a medium bowl, sift together the flour, salt, baking soda and baking powder. Grind the oats in a food processor or blender until coarse. Add the oats to the dry ingredients and stir to combine. Set aside.
In a large bowl, cream the butter and oil together. Slowly add the sugars and beat until fluffy. Add the egg and beat again until combined. Add the poppy seed mixture and beat until combined. Add the dry ingredients and beat on low until well blended. Cover and refrigerate the dough for at least 2 hours.
Preheat your oven to 350 degrees F and line two baking sheets with parchment paper. Generously flour a work surface and roll out dough to approximately 1/2 inch thick. Cut the dough into shapes using a round biscuit cutter or other shaped cookie cutters. Place 2 inches apart on cookies sheets and bake for 10 to 12 minutes or until edges are golden.