For the topping, mix together the walnuts, sugar, and cinnamon. Set aside.
Beat together the sugar and butter until light and fluffy. Add the eggs and beat them in well.
Sift the flour, baking soda, baking powder, and cinnamon into the mixture and add a pinch of salt. Mix until just incorporated. If using a mixer I just give this a couple of turns with the paddle and then scrape down with a spatula, mixing the rest of the way by hand.
Add the apples, walnuts, and vanilla and mix through until just incorporated evenly. I did this with a spatula by hand as well. Scrape into a buttered and floured loaf tin (12x4 inch).
Sprinkle topping generously over the batter. Bake in a pre-heated 180C oven for 45 minutes or until at cake tester poked in the center of the cake comes out clean. My loaf took about 50 minutes.
Cool slightly before turning out carefully...the topping will scatter a bit! So do this over your serving plate so you don’t lose any.
Serve slightly warm or at room temperature...plain or with a scoop of vanilla ice cream!