Looking for a recipe possibly from a Supercook Magazines from the 1970’s, called German Apple Cake

So much help and no acknowledgment from the OP. I wonder if it was a genuine enquiry.

I believe the recipe you're recalling is likely a version of German Apple Cake (Apfelkuchen). It usually has a cinnamon-sugar sponge base, a layer of cooked apples on top, and then a sugar-cinnamon crunchy topping. To recreate it, you could mix 1 1/2 cups of flour with 1 tsp of baking powder and 1/2 tsp of cinnamon, then combine it with 1/2 cup of softened butter, 1 cup of brown sugar, and two eggs, adding 1/2 cup of milk and some vanilla extract. Pour the batter into a greased pan, top with apple slices sprinkled with cinnamon and sugar, and finish with a topping made from a mixture of brown sugar, flour, oats, and cold butter. Bake until golden and enjoy

I had forgotten about German Apple cake, I used to make it regularly.

I think I will be baking one to take to the grandchildren this weekend!

I think the magazine you want is Supercook 30 on eBay for £1 57 plus postage. It has a German spice cake in it ( I looked in the index) Good luck.

There's some Supercook magazines for sale on Ebay.
The front covers might jog your memory if you want to buy one or ask the seller if a particular one has the recipe in it that you're after.

I also think by looking at some recipes it is an Apple Streudal cake. I wish I hadn't looked as it looks delicious and I could happily eat slice.

Here is an apple streusal cake the sounds similar to the one you describe. It sounds lovely.
everydaycooks.co.uk/apple-streusel-cake/

If you put German apple cake in search on the computer iPad etc it brings up several recipes www.bbc.co.uk/food/recipes/german_apple_cake_59663