Preheat oven to 350°F / 180°C. Grease your muffin tins and set aside.
In a large bowl, whisk together 1 can of slightly drained crushed pineapple, 2 eggs, ¼ cup of olive oil, and ½ cup brown sugar. Add ½ cup oat bran, and whisk again.
Add 1 cup spelt flour, ½ cup all purpose flour, 1 ½ teaspoons baking powder, ¾ teaspoon baking soda, ½ teaspoon salt, 1 teaspoon cinnamon, and 1 teaspoon ground ginger over the top.
Lightly whisk the dry ingredients together, then switch to a wooden spoon or spatula and stir into the wet ingredients until just combined.
Add 2 cups grated carrot and ½ cup chopped walnuts, stirring to distribute evenly through the batter. Spoon into prepared muffin tins.
Bake for 30 min, rotating the tins half way through. The muffins are done when a sharp knife inserted into the center has only a tiny bit of batter clinging to the sides.
Remove the muffins from the oven and allow to cool for 10 minutes in the muffin tins, then gently release the muffins from the tins, and turn onto their sides in the tins to fully cool.