01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, cream together butter, brown sugar, and granulated sugar until light and fluffy.
03 - Beat in eggs, one at a time, then add vanilla extract and mix until smooth.
04 - In a separate bowl, whisk together flour, baking soda, cinnamon, and salt.
05 - Gradually add dry ingredients to the wet mixture, mixing just until combined.
06 - Fold in oats, raisins, and diced apple until evenly distributed.
07 - Drop rounded tablespoons of dough onto prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 10–12 minutes, or until edges are lightly golden and centers look set.
09 - Let cookies cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.