Preheat Oven: Preheat your oven to 350°F (175°C). Grease a muffin tin or line it with paper liners.
Mix Wet Ingredients: In a medium-sized mixing bowl, combine the egg, brown sugar, sugar, melted coconut oil, sour cream, vanilla extract, and cinnamon. Stir until well combined.
Add Carrots and Zucchini: Mix the shredded carrots and zucchini into the wet ingredient mixture until evenly distributed.
Prepare Dry Ingredients: In a small mixing bowl, whisk together the flour, baking powder, baking soda, and a pinch of salt.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Fold in Nuts (Optional): If using, gently fold in the chopped pecans or walnuts until evenly distributed in the batter.
Fill Muffin Tin: Spoon the batter into the prepared muffin tin, filling each cup about 3/4 full.
Bake: Bake in the preheated oven for 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool and Serve: Allow the muffins to cool in the tin for a few minutes before transferring them to a wire rack to cool completely. The muffins will be slightly sticky but incredibly delicious!