Preheat oven to 350°F (175°C) and position the rack in the center. Line a 9×9-inch square metal pan with parchment paper or foil and lightly grease it.

Step 2: Mix the Wet Ingredients

In a large bowl, whisk together the melted butter, brown sugar, and granulated sugar for one full minute until well combined. Add the egg, egg yolk, and vanilla extract, then whisk again until smooth.

Step 3: Combine the Dry Ingredients

In a separate bowl, whisk together the flour, cinnamon, ginger, nutmeg, salt, and baking powder.

Step 4: Mix the Batter

Gradually add the dry ingredients to the wet ingredients and whisk until just combined. Be careful not to overmix. Using a spatula, fold in the shredded carrots and chopped pecans.

Step 5: Bake the Bars

Spread the batter evenly into the prepared baking pan. Bake for 22-26 minutes, or until a toothpick inserted into the center comes out clean. The bars will rise slightly but remain flat. Let them cool completely in the pan on a wire rack.

Step 6: Prepare the Cream Cheese Frosting

Using a hand or stand mixer with a paddle attachment, beat the cream cheese and butter until smooth. Gradually add the powdered sugar and vanilla extract and mix until creamy. If the frosting is too soft, chill it in the refrigerator for 20 minutes.

Step 7: Frost and Serve

Spread or pipe the frosting over the cooled bars. Garnish with chopped toasted pecans, if desired. For a neat presentation, cut the bars first, then drizzle or pipe the frosting in a zigzag pattern.