Prep the pan and oven. Heat the oven to 350°F (175°C). Grease an 8x8-inch or 9x9-inch baking pan with butter or oil, or line it with parchment for easy lifting.

Prep the apples. Core and dice the apples into small, bite-size cubes (no need to peel unless you prefer). You want about 2–2 1/2 cups of diced apples.

Mix the wet ingredients. In a large bowl, whisk 2 eggs, 1 3/4 cups milk, 1/3–1/2 cup maple syrup (to taste), 2 teaspoons vanilla, and 2–3 tablespoons melted butter or oil until smooth.

Add the dry ingredients. Stir in 2 cups rolled oats, 1 1/2 teaspoons cinnamon, 1 teaspoon baking powder, and 1/4 teaspoon salt. Mix until the oats are evenly coated.

Fold in the apples. Add the diced apples and any extras (1/2 cup chopped nuts or 1/3 cup raisins, if using). Fold gently to distribute.

Rest briefly. Let the mixture sit for 5 minutes so the oats start to absorb the liquid. This helps the bake set nicely.

Fill the pan. Pour the mixture into your prepared pan and smooth the top. Sprinkle a little extra cinnamon or a few nuts on top if you like.

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

Cool and slice. Let it cool for at least 10–15 minutes before slicing. Serve warm or at room temperature.

Serve it up. Top with a spoonful of yogurt, a drizzle of maple syrup, or a little peanut butter for extra richness.