01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together the flour, oats, cinnamon, ginger, nutmeg, baking soda, and salt in a medium bowl.
03 - Beat the butter, brown sugar, and granulated sugar in a large bowl until creamy and light, about 2 minutes.
04 - Add eggs one at a time, mixing well after each addition. Stir in vanilla extract.
05 - Gradually mix in the dry ingredients until just combined.
06 - Fold in the diced plums and raisins.
07 - Drop heaping tablespoons of dough onto prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 12–14 minutes, or until the edges are golden and centers are just set.
09 - Let cookies cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.