01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, whisk together flour, oats, baking soda, salt, and cinnamon. Set aside.
03 - In another large bowl, cream butter, brown sugar, and granulated sugar until light and fluffy, about 2–3 minutes.
04 - Beat in eggs one at a time, then add vanilla extract.
05 - Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
06 - Gently fold in diced plums and raisins.
07 - Drop rounded tablespoons of dough onto prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 12–15 minutes, or until edges are golden and centers are set.
09 - Cool on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.