Preheat oven to 350 degrees F.
Grease a standard muffin pan with nonstick spray or line with muffin liners.
In a small prep bowl, make flax egg by combining flax meal and water. Let sit for 5 minutes while you prep the other ingredients.
In a large bowl, stir together flours, old-fashioned oats, cardamom, baking soda, baking powder, and salt.
In another bowl, stir together the oil, maple syrup, and flax eggs. Mix in the grated carrots and zucchini. Add dry ingredients and stir until just combined. The batter will be thick.
Scoop batter into muffin cups, filling almost all the way. Top with chocolate chips, walnuts, pecans, pumpkin seeds, or almond slivers if desired.
Bake for 25-35 minutes, or until a toothpick inserted into the middle of the muffin comes out clean. (I often make a few mini muffins too; mini muffins will take about 15 minutes, but all ovens vary).
Let cool for 10 minutes and then remove from muffin tin with the help of a fork. The inside will be moist, but delicious!