1. Preheat oven to 350F (175C). line a parchment paper on the bottom of a 8-inch (20cm) springform pan and grease the parchment.
2. In a small bowl whisk flour, baking powder, salt and cinnamon. Set aside.
3. Peel and dice the apples into 1-inch (2.5cm) pieces.
4. In a large bowl, whisk eggs until light and fluffy, add sugar and whisk 1-2 minutes more, add vanilla extract, melted butter, rum/juice and whisk until combined. Gradually add flour mixture and mix until incorporated.
5. Fold in the apples and transfer into the prepared pan.
6. Bake for 35-40 minutes or until the cake is golden and a toothpick inserted into the center comes out clean. Let cool for 10 minutes, release from the pan and let cool to room temperature.
7.Dust with powdered sugar and serve with ice cream (optional)