Begin by softening your butter at room temperature. Finely crush the macadamia nuts using a food processor or by placing them in a zip-top bag and rolling over with a rolling pin. Preheat your oven to 325°F (163°C) and line a baking sheet with parchment paper or a silicone mat.
In a large mixing bowl, beat the softened butter, vegetable oil, and granulated sugar together using a hand or stand mixer until light and fluffy, about 3-4 minutes. This step is crucial for achieving the perfect texture.
Mix in the vanilla extract until well incorporated. This will infuse your cookies with a lovely aroma and depth of flavor.
In a separate bowl, whisk together the all-purpose flour and salt. Gradually add this to the wet mixture, mixing on low speed until just combined. Avoid over-mixing to keep the dough tender.
Gently fold the finely crushed macadamia nuts and mini chocolate chips into the dough, ensuring even distribution without breaking up the chips or nuts too much.
Using a tablespoon or cookie scoop, portion dough onto the prepared baking sheet, spacing cookies about 2 inches apart. Flatten each cookie slightly with the palm of your hand or the bottom of a glass. Bake for 18-22 minutes, or until the edges are just starting to turn golden.
Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely. Store leftover cookies in an airtight container for up to one week.