Preheat your oven to 375°F (190°C). Grease a baking dish with melted butter to prevent sticking.
Slice the apples into thin, even wedges, discarding the core. This helps them cook evenly and prevents too much crunch.
2 cups rolled oats
In a small bowl, combine the cinnamon, baking powder, and salt. This mixture will add flavor and help the oats bake up nicely.
2 cups rolled oats
In a large bowl, whisk together the eggs, milk, maple syrup, and vanilla extract until well combined. This forms the custard base.
2 cups rolled oats
Stir the dry spice mixture into the wet ingredients, blending thoroughly for an even flavor throughout.
2 cups rolled oats
Fold in the rolled oats, ensuring they are evenly coated with the liquid mixture. Let it sit for 5 minutes so the oats absorb some liquid.
2 cups rolled oats
Arrange the apple slices evenly in the prepared baking dish. Their placement creates a beautiful layered look and ensures each bite has fruit.
2 cups rolled oats
Pour the oat mixture over the apples, spreading gently so the liquid settles around the fruit for even baking.
Bake in the preheated oven for about 35 minutes, or until the top is golden brown and the oats are set with a slight jiggle.
Remove from oven and let it cool slightly for 5 minutes. The dish will be tender but hold its shape when served.
Slice into squares or spoon out generous portions, and enjoy the warm, fragrant oatmeal with its tender apples and cinnamon crust.