Sourdough Zucchini Flax Seed Muffins

Here's the recipe for Sourdough Flax Seed Muffins:
4 cups flour
4 teaspn cinnamon
1 & 1/2 teaspn baking soda
2 teaspn baking powder
1/2 teaspn salt
2 cups sugar
1/2 cup brown sugar
3/4 cup oil
3 teaspn vanilla
3 eggs, beaten
4 cups grated zucchini (blotted with paper towel)
1/3 cup flax seed
3/4 cup chopped nuts (optional)
1/2 cup sourdough starter
This recipe makes 1-13x9 inch cake and 6 extra large muffins. I sprinkled a tiny bit of coarse grained brown sugar on top and it made a nice crust on top.
Preheat oven to 325 degrees. Grease and flour the pan(s) you are using. Sift dry ingredients together. Combine sugars, vanilla, oil and eggs and beat for 2 minutes. Add zucchini and beat for 1 minute. Stir in dry ingredients until well moistened. Put batter into your chosen pan and bake 45-55 minutes until tester comes out clean (then bake another 5 minutes). (My new oven is digital-so I set the temp to 330 degrees, baked for 45 minutes, tester was clean-so I baked for another 5 minutes-don't let that clean tester fool ya. Cool and enjoy.