How to Make Simple Baked Oatmeal with Blueberries and Cinnamon

Preheat & prep pan

Position rack in center of oven and preheat to 375 °F (190 °C). Lightly grease a 9-inch square or 11×7-inch baking dish with butter or coconut oil. For guaranteed release, line with parchment leaving wings for easy lift-out.

Toss blueberries with flour

In a small bowl, gently tumble 1 cup blueberries with 1 tsp all-purpose flour or oat flour. This micro-coat creates friction so berries stay suspended rather than sinking to form a soggy bottom.

Whisk the wet squad

In a large bowl whisk 2 large eggs until homogenous. Stream in 1 ¾ cups milk, ⅓ cup maple syrup, 2 tsp vanilla, and 2 Tbsp melted butter or oil. Whisking constantly prevents scrambled eggs.

Fold in the dry goods

Sprinkle 2 cups rolled oats, 1 tsp baking powder, ¼ tsp baking soda, 1 ½ tsp cinnamon, ⅛ tsp nutmeg, and ½ tsp salt over the wet mix. Using a spatula, fold until no dry streaks remain—over-mixing activates gluten and yields chewiness we don’t want here.

Add blueberries & transfer

Gently fold in the floured berries (plus any remaining loose flour) just until dispersed. Pour batter into prepared dish and jiggle to level; berries should appear evenly scattered.

Top & bake

If you like a bakery-style crown, scatter 2 Tbsp coarse sugar or granola over surface for crunch. Bake 32–38 minutes until the center springs back lightly and a toothpick inserted at 45° angle comes out with just a few moist crumbs.

Rest & serve

Cool 10 minutes—this sets the custard and prevents molten berry burns. Serve warm squares solo, or go deluxe with a drizzle of cream and extra maple. Leftovers? See storage section.

Expert Tips

Oven calibration

If your oven runs hot, reduce temp to 350 °F and add 5 min. An inexpensive oven thermometer saves guesswork.

Overnight option

Assemble through Step 5, cover tightly, refrigerate up to 12 hr. Bake straight from cold, adding 3–4 min.

Moisture meter

If you sub applesauce for butter, reduce milk by 2 Tbsp to keep the custard ratio balanced.

Double batch hack

Bake in a 9×13 pan for 40–45 min; cool, slice into 15 squares, freeze flat on a tray, then bag.

Flavor bloom

Bloom spices: microwave butter 20 sec, stir in cinnamon/nutmeg, cool slightly before adding. Depth unlocked.

Texture tweak

For extra chew, substitute ½ cup quick oats; for extra creaminess, replace ½ cup milk with Greek yogurt.

Variations to Try

Apple-Cranberry: Swap blueberries for diced Honeycrisp + dried cranberries, add ½ tsp cardamom.
Banana-Nut: Sub ½ cup mashed ripe banana for maple, fold in ½ cup toasted walnuts.
Chocolate-Almond: Replace berries with dark-chocolate chips, use almond extract, top with sliced almonds.
Savory-Sweet: Omit sugar, add ½ cup shredded sharp cheddar + chopped scallions for brunch alongside sausage.
Tropical: Use coconut milk, fold in diced mango + toasted coconut; finish with lime zest.

Storage Tips

Refrigerate: Cool completely, cover tightly or transfer to airtight container. Keeps 5 days; reheat single squares in microwave 30–40 sec with a damp paper towel.

Freeze: Cool, slice into 9 squares, wrap each in plastic then foil. Freeze up to 3 months. Thaw overnight in fridge or microwave from frozen 60–90 sec.

Meal-prep portions: Press parchment into muffin tin, fill cups ¾ full, bake 18–20 min for grab-and-go oat-cups.