Preheat the oven to 350°F. Grease an 8×8 inch baking dish or a similar sized dish with butter.

In a large bowl, combine the rolled oats, brown sugar, baking powder, cinnamon, nutmeg, cardamom, ginger, and salt. Stir to evenly distribute the spices.

In a separate bowl, whisk together the eggs, milk, heavy cream, vanilla extract, melted butter, and honey (if using).

Pour the wet ingredients into the dry mixture and stir until everything is well combined.

Gently fold in the fresh or frozen blueberries and the sliced banana.

Pour the mixture into the prepared baking dish. Use a spatula to spread it evenly. You can add a few extra blueberries and banana slices on top for presentation.

Bake in the preheated oven for 35 to 40 minutes, or until the top is golden brown and the center is set (it shouldn’t jiggle when you shake the dish lightly).

Let the baked oatmeal cool for a few minutes before serving. Serve blueberry baked oatmeal with delicious toppings like butter, milk, cream, maple syrup, or honey.