1. Preheat oven to 350°F. In a medium bowl, beat butter, brown sugar, and vanilla with an electric mixer on medium speed until well blended.
2. Add flour, oatmeal, cinnamon, and salt and beat on low speed until a stiff dough forms, scraping down side of bowl frequently with a rubber spatula.
3. Divide dough in half. On a lightly greased cookie sheet, roll out one half of dough with a floured rolling pin to make an 8-inch round. Score round into 8 wedges. Repeat with remaining dough on a second cookie sheet.
4. Bake rounds 12 to 15 minutes, or until edges are golden brown. Let cool 2 minutes on sheets, then remove to racks and let cool completely. To serve, break into wedges where scored. Store in a tightly covered container.