Preheat and prep. Heat the oven to 350°F (175°C). Grease a 9x9-inch baking dish or line it with parchment for easy removal.

Combine dry ingredients. In a large bowl, mix 2 cups rolled oats, 1 teaspoon baking powder, 1 ½ teaspoons cinnamon, and ¼ teaspoon salt. Add a pinch of nutmeg if you like.

Whisk the wet ingredients. In a separate bowl, whisk 1 ¾ cups milk, 2 large eggs, ⅓ cup maple syrup, 1 teaspoon vanilla, and ½ cup unsweetened applesauce. If using melted butter or coconut oil instead of applesauce, let it cool slightly before whisking in.

Fold in apples and extras. Core and dice 2 medium apples into small cubes (about 2 cups). Stir them into the wet mixture along with ⅓ cup chopped nuts and ⅓ cup raisins if using.

Combine wet and dry. Pour the wet mixture over the dry ingredients and stir until everything is evenly moistened. The batter will be loose—that’s good.

Pour and smooth. Spread the mixture into the prepared dish. Sprinkle a little extra cinnamon on top, or add a few thin apple slices for a pretty finish.

Bake. Bake for 35–40 minutes, until the center is set and the edges are lightly golden. A toothpick should come out mostly clean.

Rest and serve. Let it cool for 10 minutes to set. Slice and serve warm as-is, or top with yogurt, a drizzle of maple syrup, or a splash of warm milk.