Step 1

Preheat oven to 325°F and grease a 8x8 pan with baking spray. Line the bottom with parchment paper, set aside.

Step 2

In a large saucepan, combine water and raisins and bring to a gentle boil, cooking for 10 minutes. Add vegetable oil to the boiled mixture. Allow the mixture to cool to room temperature.

Step 3

Combine flour, sugar, pumpkin spice mix, baking soda, and salt in a bowl, whisking to break up any lumps.

Step 4

Mix the dry-ingredients into the boiled raisin mixture. Add in egg and walnuts (if using).

Step 5

Pour batter into prepared pan and bake until a toothpick inserted comes out mostly clean with a few moist crumbs about 35 to 40 minutes. Cool completely before assembling.

Step 6

In a large, bowl beat cream cheese and butter until smooth and lump free, about 2 to 3 minutes. Gradually add powdered sugar and salt, beating until smooth.

Step 7

Remove the cake from the baking pan and place it on a cutting board.

Step 8

Slice the cake in half.

Step 9

Transfer one layer to a serving tray and apply the frosting on top.

Step 10

Top with the second layer and top with remaining frosting.

Step 11

For a grooved pattern, use a fork to draw lines in the frosting.