Preheat oven to 350°F (175°C).

Spread pie filling evenly in the bottom of a baking pan.

In a separate bowl, combine flour, sugar, and salt.

Sprinkle the flour mixture evenly over the pie filling.

In another bowl, combine eggs, vanilla, oil, and half of the chopped walnuts.

Mix the egg mixture well until combined.

Pour the egg mixture over the ingredients in the baking pan.

Stir gently until the ingredients are just blended.

Bake in the preheated oven for 40 to 50 minutes, or until a toothpick inserted into the center comes out clean.

Remove the cake from the oven and let it cool slightly.

While the cake is still warm, prick it all over with a fork.

Pour a desired topping (such as a glaze or simple syrup) over the warm cake.

Sprinkle the remaining chopped walnuts evenly over the top of the cake.

Let the cake cool completely before serving.