This is a classic version of an American favorite. The carrot studded cake is moist yet delicate and the spicy, sweet flavors are well balanced. As for the frosting, while I love a good cream cheese frosting when linked with carrot cake, I chose to pair the cake here with an orange buttercream for its delicate flavor and silky texture.
- Position a rack in the center of the oven and preheat the oven to 350°F (180°C/gas mark 4).
- Lightly grease and flour the bottom and sides of the half-sheet pan.
- Combine the flour, granulated and brown sugars, cinnamon, baking soda, ginger, salt, and nutmeg in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-low speed until well blended, about 1 minute. Add the carrots, oil, eggs, orange zest, and vanilla. Beat on medium-low speed until combined, about 30 seconds. Increase the speed to medium and beat until well blended, about 1 minute more.
- Scrape the batter into the prepared pan and, using an offset spatula, spread evenly. Bake until a toothpick inserted in the center comes out clean, 22 to 24 minutes.
- Let the cake cool in the pan. Assemble and serve the cake
- Spread the frosting evenly over the cake layer. Just before serving, scatter the nuts on top of the cake, if desired.
- Place the flour in a small saucepan. Tipping the pan to one side, add about 2 tablespoons of the milk and whisk until the mixture forms a thick, smooth paste. Add another 2 tablespoons milk and whisk until blended. Set the pan on the counter and gradually add the remaining milk, whisking until the mixture is smooth.
- Place the pan over medium heat and, whisking constantly, bring the mixture to a boil. Cook, continuing to whisk constantly, for 1 minute. Remove the pan from the heat, add the sugar and measured salt, and whisk until the sugar is dissolved.
- Pour the mixture through a fine-mesh sieve set over a medium bowl (do not press down). Scrape the underside of the sieve into the bowl and discard the floury remnants in the sieve. Set aside, stirring occasionally, to cool completely. (For faster cooling, set the bowl over a larger bowl filled with ice and a little water, stirring and scraping the sides frequently until chilled to room temperature.)
- In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium speed until smooth, about 1 minute. Add the cooled sugar mixture and 2 tablespoons of the vanilla and beat on medium speed until smooth and well blended, about 2 minutes more. If the mixture looks grainy or “broken,” keep mixing until the texture is smooth. Taste and add more salt and vanilla as needed. The flavor should be vibrant.
- Store the buttercream, well covered or in heavy-duty zip-top bags with the air pushed out, in the refrigerator for up to 4 days or in the freezer for up to 3 months. Before using, bring to room temperature and beat until smooth and light. Before using, bring to room temperature and whisk until smooth and warm enough to spread.
- For Citrus Add-In: Stir 3 tablespoons finely grated orange or lemon zest into the frosting.