Preheat the Oven: Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
Mix Wet Ingredients: In a large mixing bowl, combine the mashed sweet potatoes, melted butter, honey (or maple syrup), eggs, milk, and vanilla extract. Whisk until smooth and fully incorporated.
Combine Dry Ingredients: In another bowl, whisk together the all-purpose flour, whole wheat flour, baking powder, baking soda, and salt until well blended.
Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Be careful not to overmix; a few lumps are fine.
Add Herbs and Cheese: Fold in the chopped rosemary, thyme, and grated Parmesan cheese (if using) into the batter.
Fill Muffin Tins: Using a spoon or ice cream scoop, fill each muffin cup about 0.75 full with the batter.
Bake: Place in the preheated oven and bake for 20-25 minutes or until the muffins are golden brown on top and a toothpick inserted into the center comes out clean.
Cool: Remove the muffins from the oven and allow them to cool in the tin for 5 minutes. Transfer them to a wire rack to cool completely.
Serve: Enjoy the muffins warm, or store them in an airtight container for up to three days. They are delightful on their own or spread with a bit of herb butter for an extra touch!