This pineapple upside-down cake is given a delicious twist with the addition of a cinnamon streusel topping. The Thermomix makes it easy to mix the batter, and the cake bakes up perfectly every time. The pineapple rings and brown sugar topping add just the right amount of sweetness, while the cinnamon streusel adds a delicious crunch. Serve warm with a scoop of vanilla ice cream for a dessert that's both comforting and delicious.