Preheat your oven to a cozy 300°F (149°C). Grab a large baking sheet and line it with parchment paper or a silicone mat for easy cleanup. Spread your chopped walnuts onto the baking sheet and slide them into the oven for about 6 to 8 minutes. Halfway through, give the pan a shake to make sure they toast evenly. Once they smell divine, remove them from the oven and let them cool for about 10 to 15 minutes.

Next, let’s get the baking pans ready. Increase your oven’s temperature to 350°F (177°C). Grab two or three (9-inch) cake pans and grease them well with nonstick spray. Line the bottoms with parchment paper rounds, greasing the paper too. This little trick will help your cakes release flawlessly from the pans.

In a large mixing bowl, whisk together the light brown sugar, granulated sugar, vegetable oil, eggs, applesauce, and vanilla extract. Go at it until it’s well combined and no sugar lumps are in sight. You’ll want each ingredient to be welcomed into the mix.

In another sizeable bowl, blend the all-purpose flour, baking powder, baking soda, salt, and all those delightful spices: cinnamon, ginger, nutmeg, cloves, and allspice. Use a whisk to get everything mixed nicely.

Now, pour the wet mixture into the dry ingredients. Using a spatula or a sturdy wooden spoon, fold them gently together until just combined. Be careful not to overmix; we want that cake to be soft and tender. Once combined, gently fold in the grated carrots and one cup of the previously toasted walnuts.

Divide the batter evenly among the prepared pans. If you’re using three pans, pop them in the oven for about 20 to 25 minutes. If you opted for just two, expect them to take about 30 to 35 minutes. Keep an eye out for a toothpick; it should come out clean when poked in the center.

Once baked, set the pans on a cooling rack for about an hour. After, run a knife along the edges and gently remove the cakes. Peel the parchment paper off and let them cool completely on the rack before frosting. This part is crucial; if the cakes are warm, the frosting will slide right off!

While the cakes cool, let’s whip up a frosting that’s smooth and creamy. In a large bowl, use a stand mixer or handheld mixer to beat the cream cheese and softened butter until you achieve a silky consistency—about 2 minutes. Scrape down the sides of the bowl to make sure everything's coming together nicely. Next, add the confectioners’ sugar, vanilla extract, and a pinch of salt. Start on low speed (yes, we don’t want an icing cloud!) for about 30 seconds, then crank it to high for 3 minutes. Give it a taste — if it’s too thick, add a splash of milk; too thin? Toss in more sugar!

Now comes the fun part—assembly! Using a large serrated knife, trim a thin layer off the top of each cooled cake layer to create a level top. Place one layer on your cake stand or turntable, and layer it with 3/4 to 1 cup of frosting on top. Stack the second layer upside down (this helps with stability) and add the same amount of frosting. Finish with the third layer right side up. Cover the top and sides of the cake generously with the remaining cream cheese frosting, and top with the reserved toasted nuts for that delightful crunch.

For the final touch, chill that beauty in the fridge for at least 20 minutes before slicing. This waiting game ensures it holds its shape when you cut it. If you plan to keep it longer than 4 hours, I recommend taking it out about 2 hours before serving to let it come to room temperature.