This does not look pretty, and that's not all down to my non-existent photography skills. The cake turned out too shallow to show properly that it is layered, with a streusel of cinnamon, sugar, chopped pecans and chocolate chips in the middle, as well as liberally sprinkled over the top. It's delicious though, so I'm still including it here!
I made half of this recipe, using an 8" square tin, even though 'scale downs' which end up using fractions of eggs usually annoy me. The cat certainly appreciated half an egg! I felt I couldn't justify using 350g chocolate chips in something which we might not like, and 32 portions sounded enormous - far more than three of us could eat. In the event, I couldn't cut half the cake into 16 portions - I only got 9 pieces of a decent size! What's the point in being unrealistic about how much cake someone is likely to eat?
I made one change to the recipe - I used demerara sugar for the portion of sugar that went into the streusel mix - both for colour and crunch. I would recommend making the streusel in two parts. It was very difficult (nay, impossible!) to mix the sugar and cinnamon thoroughly with the nuts and chocolate, then divide it into two. It would have been easier to manage if the sugar and cinnamon was in one bowl, and the chocolate and pecans in another.
It was very difficult to spread half the batter over the base of the tin, and even more difficult to spread the second half over the streusel layer, as the amount of batter seemed so meagre. I think ideally, halving the streusel, but only reducing the batter by 1/3 would have been better, making a deeper cake which I could have cut into 12 good sized portions.