For an even richer flavor, try browning the butter before adding it to the wet ingredients. The nutty notes will elevate the overall taste profile. Feel free to experiment with different nuts and seeds, such as walnuts, pecans, or pumpkin seeds, to customize the texture and flavor to your liking. These baked oatmeal cups can be stored in an airtight container in the refrigerator for up to 5 days or frozen for up to 2 months. Reheat gently in the microwave or oven before serving.