Prep the oven and pan: Preheat your oven to 350°F (175°C). Grease a 9x9-inch or similar baking dish with butter or coconut oil. This helps the edges crisp and the bake release cleanly.

Mix the dry ingredients: In a large bowl, stir together 3 cups rolled oats, baking powder, cinnamon, and salt. If using nuts or raisins, add 1/2 cup now so they’re evenly distributed.

Whisk the wet ingredients: In another bowl, whisk the eggs, milk, maple syrup, applesauce, and vanilla until smooth. The applesauce adds moisture and a little sweetness without extra sugar.

Chop the apples: Core and dice the apples into small, bite-size pieces (no need to peel unless you prefer). Aim for even pieces so they soften at the same rate.

Combine: Pour the wet mixture into the dry ingredients and stir just until combined. Fold in the chopped apples. The mixture will look loose—that’s good.

Transfer to the pan: Pour into the prepared baking dish and spread evenly. If you like, sprinkle extra nuts or a pinch of cinnamon on top for texture and color.

Bake: Bake for 35–40 minutes, until the center is set and the top is lightly golden. A toothpick inserted in the center should come out mostly clean.

Rest and slice: Let it cool for 10–15 minutes so it sets up and slices neatly. Cut into squares and serve warm as is or with a splash of milk or a dollop of yogurt.

Make it yours: For a crisper top, broil for 1–2 minutes at the end, watching closely. For a softer, more custardy texture, reduce bake time by a couple of minutes.