Preheat your oven to 350°F and line your baking sheets with silicone mats. In your mixer bowl, beat the softened butter with both sugars on medium-high speed for about 3 to 4 minutes. You're looking for a pale, fluffy texture, which means enough air has been worked into the mixture for a tender cookie.
Lower the mixer speed and add the eggs one at a time, letting each one blend in fully before adding the next. Pour in the vanilla extract and mix until the batter looks smooth and glossy. If it looks slightly separated, just keep mixing a little longer until it comes together.
Whisk the flour, baking soda, and salt together in a separate bowl, then sift them for extra smoothness. Add this to the wet mixture gradually on low speed, stopping as soon as the flour disappears into the dough. Split the dough into two bowls, then stir the dragon fruit powder into one half until it turns a deep pink.
Gently fold the chopped pineapple and white chocolate chips into both halves of the dough using a spatula. Take a small piece of pink dough and a small piece of plain dough, press them together, and twist lightly to create a marbled pattern. Scoop these onto your prepared baking sheets, leaving about two inches between each ball.
Bake the cookies for 10 to 12 minutes, until the edges look set and the centers still look a touch soft. Let them rest on the hot pan for about 5 minutes before moving them, since they're still finishing their bake during this time. Transfer to a wire rack to cool completely before serving.