Preheat oven to 425° F. Line a standard 12-cup muffin pan with baking cups or spray with non-stick cooking spray.
In a small bowl, stir together sour cream and oats until combined.
In a medium bowl, whisk together gluten free flour blend, baking powder, baking soda, and salt until combined.
With an electric mixer, in a large bowl, beat together oil, sugars, and egg until completely combined.
Add oat mixture to oil mixture and stir until completely combined.
Stir in the flour mixture until just combined, then fold in the cranberries.
Divide the batter evenly between the prepared muffin cups.
Bake at 425° for 5 minutes, then reduce oven temperature to 350° and continue baking for an additional15 minutes. The muffins are done when a toothpick inserted into the center comes out clean.
Allow the muffins to cool for 5 minutes in the pan, then transfer to a wire rack to cool completely.
Notes
Check the ingredients of your gluten free flour blend for xanthan gum. If your flour blend doesn’t contain it, try adding ½ teaspoon to the recipe.
If you’re making these muffins for someone with Celiac disease, use certified gluten free oats. When the oats aren’t processed in a gluten free facility, they may pick up gluten in a facility that also processes wheat and barley.
Use a large scoop to fill the muffin cups with batter. This will keep the muffins similar in size and ensure even baking time.
Start the baking time at 425 degrees and then lower the temperature to 350 degrees after a few minutes. The higher temperature creates domed muffin tops and the lower temperature keeps the insides tender.
Remove the muffins from the pan to finish cooling on a wire rack. If you leave the muffins in the pan to cool, the bottoms of the muffins may become soggy.