1. 1. Prepare for Baking: First, preheat your oven to 350°F (175°C). Next, lightly grease and flour a 9×13-inch baking pan, or line it with parchment paper for easy removal.

2. 2. Combine Dry Ingredients: In a large bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg. Set this aside.

3. 3. Mix Wet Ingredients: In a separate medium bowl, combine both sugars, vegetable oil, eggs, and vanilla extract. Whisk until smooth and well combined.

4. 4. Combine Wet and Dry: Pour the wet ingredient mixture into the dry ingredients. Mix just until combined; avoid overmixing. Then, fold in the grated carrots and optional nuts.

5. 5. Bake the Bars: Pour the batter evenly into your prepared baking pan. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

6. 6. Cool Completely: Remove the pan from the oven. Allow the bars to cool completely in the pan on a wire rack. This step is crucial before frosting the Carrot Cake Bars with Cream Cheese Frosting.

7. 7. Make the Frosting: While the bars cool, beat the softened cream cheese and butter in a medium bowl with an electric mixer until light and fluffy. Gradually add the powdered sugar, one cup at a time, beating until smooth. Finally, mix in the vanilla extract.

8. 8. Frost and Serve: Once the carrot cake bars are completely cool, spread the cream cheese frosting evenly over the top. Cut into squares and enjoy your perfect Carrot Cake Bars with Cream Cheese Frosting!