The streusel can be made up ahead of time and frozen. It will make more than you need for this recipe. Another great idea is to use a couple of different kinds of baking apples, as they will each lend their own flavors and nuances to the dish.
In a large bowl, combine all the streusel topping ingredients. Crumble together until well combined. Set aside.
For the apple crisp, in another bowl combine apple mixture ingredients. Pour the apple mixture into a greased 23 cm square baking dish. Top with a generous amount of the streusel topping. Place on the wire rack set on position 2. Turn the convection steam oven on by selecting the Auto Steam Bake Mode set to 175°C. Bake until golden brown and bubbly. Approximately 45 minutes.