Place butter and sugar in a bowl and use a stand mixer to beat until light in color. Add egg and milk and beat to combine. Put mixer on low speed, gradually add the flour mix, and beat until the mixture pulls away from the side of the bowl. Divide the dough in half, cover with a plastic bag, and refrigerate for 2 hours.
Preheat oven to 375 degrees F.
Sprinkle the surface where you will roll out the dough with flour or powdered sugar. Remove the dough from the refrigerator, sprinkle the rolling pin with flour, and roll out the dough to ¼-inch thick.
Cut into rectangles and then start in the middle of the rectangle creating a triangle that only goes until half the length of the rectangle. From there cut another two triangles on the side just as in the photo, or you can use crown-shaped cookie cutters.
Grease a baking sheet with cooking oil and place the cookies shaped dough on top. Bake between 7 and 9 minutes at 375 Fahrenheit.
Let the cookies cold down.