Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.

In a medium bowl, whisk together flour, baking soda, salt, and cinnamon.

Cream together softened butter and granulated sugar until pale and fluffy.

Add eggs one at a time, mixing well after each addition, then add vanilla extract.

Gradually stir the dry ingredients into the wet ingredients until just combined.

Fold in grated apples and walnuts into the batter.

Pour the batter into the baking pan and bake for 30-35 minutes until golden brown.

Cool the cake in the pan for 10 minutes before transferring to a wire rack to cool completely.

Prepare the frosting by beating together cream cheese and unsalted butter until smooth, then mix in powdered sugar and vanilla.

Frost the cooled cake generously with the cream cheese frosting.