Prepare the cake mix according to the package directions, adding ½ cup golden raisins to the batter if desired. Bake as directed.

Let the cake cool for 15 minutes.

Poke it: Using the back of a wooden spoon or a straw, poke holes in the cake about 1 inch apart.

Make the filling: In a bowl, whisk together the sweetened condensed milk, caramel sauce, and cinnamon until well combined.

Carefully pour the mixture into the holes, ensuring it soaks into the cake.

You may have some filling left over, and that's ok. Fill all of the holes, but don't overly saturate the cake with the filling.

Cover and refrigerate for 1–2 hours to allow the cake to set.

Make the frosting: In a mixing bowl, beat the softened butter and cream cheese with an electric hand mixer or a stand mixer fitted with a whisk attachment until light and fluffy.

Add the vanilla extract and 2 cups powdered sugar, mixing on medium-low speed until smooth. Scrape down the sides of the bowl, then add the remaining powdered sugar. Continue mixing until well combined and creamy.

Spread the frosting evenly over the chilled cake.

Cover and refrigerate for at least 2 hours to allow the frosting to set.

Toast the walnuts: In a dry pan over medium heat, toast the walnuts for 2–4 minutes, stirring frequently, until fragrant. Be careful not to burn them.

Chop the toasted walnuts and sprinkle them over the cake right before serving.

Slice, serve, and enjoy! Refrigerate any leftovers.