Sweetened Condensed Milk (optional): poke holes in cooled cake, pour over, refrigerate overnight, then frost as usual

For the cake:
2 1/2 cups all-purpose flour
1 1/4 teaspoons baking powder
1 teaspoon baking soda
1 teaspoon ground cinnamon
1/2 teaspoon freshly ground nutmeg
1/4 teaspoon ground allspice
1/2 teaspoon fine salt
4 large eggs
1 1/3 cups granulated sugar
1/2 cup packed light brown sugar
1 cup vegetable oil
1/2 cup whole-milk plain yogurt
1 1/2 pounds carrots, peeled and grated on the large holes of a box grater or with a metal grating attachment in a food processor (about 5 cups)
1 cup walnut halves (about 3 ounces) (optional)
golden raisins (optional)
sweetened condensed milk (optional)

For the frosting, or use store-bought cream cheese frosting:
2 sticks unsalted butter, at room temperature
2 (8-ounce) packages cream cheese (1 pound), at room temperature
2 cups powdered sugar, sifted
1 teaspoon vanilla extract

2 1/2 cups all-purpose flour 1 1/4 teaspoons baking powder 1 teaspoon baking soda 1 teaspoon ground cinnamon 1/2 teaspoon freshly ground nutmeg 1/4 teaspoon ground allspice 1/2 teaspoon fine salt 4 large eggs 1 1/3 cups granulated sugar 1/2 cup packed light brown sugar 1 cup vegetable oil 1/2 cup whole-milk plain yogurt 1 1/2 pounds carrots, peeled and grated on the large holes of a box grater or with a metal grating attachment in a food processor (about 5 cups) 1 cup walnut halves (about 3 ounces) (optional) 2 sticks unsalted butter, at room temperature 2 (8-ounce) packages cream cheese (1 pound), at room temperature 2 cup s powdered sugar, sifted 1 teaspoon vanilla extract

For the cake:
1. Heat the oven to 350°F and arrange a rack in the middle.
2. Place the flour, baking powder, baking soda, cinnamon, nutmeg, allspice, and salt in a large bowl and whisk to aerate and break up any lumps; set aside.
3. Place the eggs, sugars, oil, and yogurt in a large bowl and whisk until the eggs are broken up and the mixture is thoroughly combined. Using a rubber spatula, fold in the flour mixture until just combined. Stir in the carrots until evenly mixed.
4. Pour the batter into a 13-by-9-inch glass baking dish (no need to coat with butter), smoothing it into the corners with the rubber spatula.
5. Bake, rotating the dish after 20 minutes, until a toothpick or cake tester inserted in the center comes out dry with just a few crumbs, about 40 to 50 minutes total. Transfer to a wire rack to cool completely before frosting, at least 2 hours. Meanwhile, toast the nuts.
6. Place the nuts on a baking sheet and bake until lightly browned and fragrant, about 10 minutes. Transfer the nuts to a cutting board to cool slightly, coarsely chop them, and set aside.

For the frosting:
1. Place the butter and cream cheese in the bowl of a stand mixer fitted with a paddle attachment and beat on medium-high speed until light, fluffy, and fully incorporated, about 3 minutes.
2. Stop the mixer and scrape down the sides of the bowl and the paddle with a rubber spatula. Add the powdered sugar and vanilla. Turn the mixer to low and mix until the sugar is incorporated, about 30 seconds.
3. Stop the mixer and scrape down the sides of the bowl and the paddle again. Turn the mixer to medium-high speed and mix until the frosting is creamy and fluffy, about 3 minutes.
4. Spread all of the frosting in an even layer over the cooled cake and evenly sprinkle the toasted nuts over the frosting. If you don’t plan to eat the cake within 4 hours, cover it with plastic wrap and refrigerate for up to 3 days. Before serving, let the cake sit at room temperature for about 45 minutes to take the chill off.