1. Drain the crushed pineapple in a fine-mesh strainer set over a bowl, reserving the juice. Let the fruit sit for a few minutes so most of the liquid drips out.

2. Measure 1 cup of the reserved pineapple juice into a large mixing bowl. Whisk in the instant vanilla pudding mix until smooth and thickened, 1–2 minutes. If the mixture seems too thick, whisk in another tablespoon of juice.

3. Add the sour cream to the pudding mixture and whisk until completely blended with no streaks remaining.

4. Switch to a spatula and gently fold in the Cool Whip whipped topping, working slowly so you keep the mixture light and fluffy.

5. Fold in the drained crushed pineapple, mini marshmallows, shredded coconut, and chopped pecans if using. Stir just until everything is evenly distributed.

6. Transfer the pineapple fluff to a serving bowl, smoothing the top with the back of a spoon. Cover and refrigerate for at least 1 hour, or up to 4 hours, to allow the flavors to meld and the marshmallows to soften.

7. Right before serving, garnish with pineapple tidbits and a sprinkle of extra shredded coconut. Serve chilled and enjoy.