Preheat the oven to 190C on hot air and line a 12-hole muffin tin with paper cases. Mix the eggs, sugar, milk and melted butter in a large bowl. Sift the flour, baking powder, salt and cinnamon into the bowl. Stir well to combine. Add the chopped apple and lightly mix. Using half of the mixture, quarter-fill each of the muffin cases with the mixture and top with a few pieces of toffee. Cover with the remaining filling so the cases are half full. Bake for 20 minutes until well risen and golden. Transfer to a wire rack to cool. Serve warm or cold.