Pineapple Upside-Down Muffins

Ingredients
Topping
* 2 tablespoons packed light brown sugar
* 2 tablespoons chopped walnuts, or pecans (optional)
* 1 10-ounce can pineapple slices

Muffins
* 3/4 cup whole-wheat flour
* 3/4 cup all-purpose flour
* 2 teaspoons baking powder
* 1/2 teaspoon baking soda
* 1/4 teaspoon salt
* 1 tablespoon ground cinnamon
* 2 large eggs
* 1/2 cup packed light brown sugar
* 1/4 cup canola oil
* 2 tablespoons pineapple juice, or orange juice
* 1 teaspoon vanilla extract
* 1 8-ounce can crushed pineapple, (not drained)
* 1 cup grated carrot, (1 large)
* 1/2 cup old-fashioned oats
* 3/4 cup raisins, preferably baking raisins (see Ingredient note)
* 1/4 cup chopped walnuts, or pecans (optional)

1. Preheat oven to 400°F. Coat 12 muffin cups with cooking spray.

2. To prepare topping: Sprinkle 1/2 teaspoon brown sugar into each muffin cup. Sprinkle nuts, if using, over the sugar. Stack pineapple slices and cut into 6 wedges. Place 2 wedges in each muffin cup.

3. To prepare muffins: Whisk whole-wheat flour, all-purpose flour, baking powder, baking soda, salt and cinnamon in a large bowl.

4. Whisk eggs and brown sugar in a medium bowl until smooth. Whisk in oil, juice and vanilla. Stir in crushed pineapple. Make a well in the dry ingredients; add the wet ingredients and stir with a rubber spatula until just combined. Stir in carrot, oats, raisins and nuts, if using. Scoop the batter into the prepared muffin cups (they'll be quite full).

5. Bake the muffins until the tops are golden brown and firm to the touch, 15 to 25 minutes. Immediately loosen edges and turn muffins out onto a baking sheet. Restore any stray pineapple pieces and nuts. Let cool for at least 10 minutes. Serve upside-down, either warm or at room temperature.