Preheat the oven to 400 degrees. Line 15 muffin cups with paper liners.

In a medium bowl combine the flour, granola, baking powder, and salt. Mix and set aside.

In a large bowl cream together the butter, brown sugar, and white sugar. Stir in the crushed pineapple.

Add in the egg and mix well. Stir in the vanilla.

Add half of the flour mixture to the butter mixture and mix well. Stir in the milk. Add the remaining flour mixture and mix until incorporated.

Pour the batter into the prepared muffin cups, filling each one ¾ of the way full.

In a small bowl combine the granola, brown sugar, and pineapple juice. Sprinkle over top of the muffins.

Bake for 16-18 minutes or until the tops have browned and a toothpick inserted into the center comes out clean.