To make the spiced cake: Preheat oven to 180C/350F/Gas 4 and grease three 9-inch baking pans with baking spray or butter.

Sift together the flour, baking soda, and ground spices into a large bowl. Add the salt and stir to combine. Set aside.

Mix the buttermilk and vanilla extract together in a bowl and set aside.

Using an electric mixer, beat together the butter and sugars until light and fluffy.

Mix in the eggs one at a time until combined before adding another egg.

Alternate adding the flour mix and buttermilk mixture to the butter, sugar, and eggs combining well between each addition.

Divide the batter between the 3 pans and bake in the oven for 30 minutes or until a toothpick comes out clean.

Cool in pans for 5 minutes before transferring to a wire rack to cool completely.

To make the apple pie filling: Toss the chopped apples with the lemon juice in a large bowl. Set aside.

Place the sugars, cornstarch, cinnamon, nutmeg, salt, and water into a large saucepan and bring to a slow boil on medium heat.

Once water is boiling, add the apples and bring back to a boil for about 10 minutes.

Remove from the stove and allow it to cool completely. The sauce will start to thicken as it cools.

To make the pie layer: Line two baking sheets with parchment paper. Place the pie crusts onto the cookie sheets and brush with beaten egg. Bake in the oven (same temperature as cake) for 15 minutes until golden brown. Allow to cool completely.

To make the walnut crumble: Keep the oven heated at the same temperature as before and line a baking sheet with parchment paper.

In a medium bowl, whisk together the flour, oats, chopped walnuts, baking powder, salt, and cinnamon until combined.

Cut the butter into cubes and place them into the flour mixture. Use the tips of your fingers to rub the in the butter to make the crumble.

Pour the crumble mixture onto the baking sheet and bake for 8 minutes. Remove from the oven and mix the crumble before returning to the oven for a further 8 minutes. Remove and cool completely. When cooled, break up into pieces.

To make the cinnamon frosting: Beat all of the ingredients together with an electric mixer until fluffy, smooth and forms stiff peaks - about 5 minutes. You can add more powdered sugar or cream to adjust the mixture as required.

Scoop about 2 cups of the frosting into a piping bag fitted with a large round tip and set aside.

To build the cake: Place the first layer of cake onto a 10-inch cake board (and onto a cake stand if using). Scoop about 1 cup of frosting onto the cake layer and spread evenly.

Place a pie crust onto frosting then pipe two large, stacked rings around the pie crust.

Fill in the middle with half of the apple pie filling. Place the second cake layer on top.

Repeat steps with the second cake layer, and add the third cake layer to finish.

Using the remaining frosting to cover the entire cake. You may find it easier to chill the cake first so that the frosting inside hardens.

Create a ring of crumble around the top edge of the cake and refrigerate before serving.

Cut into slices and enjoy!