Preheat oven to 425 degrees and prepare muffin tins (grease or line) or silicone muffin cups. This recipe will make about 15 muffins.
Mix the crumb topping ingredients in a small bowl, blending by hand or with a fork until crumbly.
In a large bowl, sift together the flour, baking soda, baking powder, salt and spices.
In a medium-sized bowl, whisk together the eggs, oil, brown sugar and sourdough starter.
Add the sourdough mixture to the dry ingredients and gently fold in until the flour is mostly dissolved, making sure not to over mix.
Fold in the carrots until evenly mixed throughout; the batter will be thick.
Scoop the batter into the prepared muffin cups, filling about 3/4 full.
Sprinkle about 1-1/2 tablespoons of the crumb topping over the top of each muffin.
Bake at 425 degrees for 5 minutes. Turn the heat down to 350 degrees (don’t open the door) and cook for 15-20 minutes longer, until the muffins are lightly browned and cooked through.
The original recipe for these amazing muffins can be found here.