Heat oven to 350F/180C. Butter and line an 8-in/20-cm baking pan (or Springform pan) with parchment paper, buttering the sides.
In a small bowl, combine milk and lemon juice. Allow to rest for a minimum of 5 mins, or till the milk appears to have thickened and curdled, then add melted butter and vanilla extract.
In a large mixing bowl, whisk eggs and sugar until frothy. Sift in flour, cinnamon, baking powder, baking soda, and salt directly over the bowl, then whisk until just combined.
Pour in the milk mixture, stirring gently with a spatula until incorporated.
Fold in the apples until evenly distributed.
Transfer to baking pan, smooth the top (an offset spatula works well here), sprinkle slivered almonds on top.
Bake 30-35 mins, or until a toothpick inserted in centre comes out clean. Allow to cool in the pan. To remove from pan (if not using a Springform), cover the top of the cake with fresh parchment paper, flip onto a plate, then flip it back onto your cake dish.