Preheat the oven to 350˚F.
Slice the apples into a large bowl, or directly into a pie plate or baking dish.
Add the cranberries, sugar and cinnamon and toss to coat. (If you mixed them in a bowl, pour into the baking dish, including any sugar at the bottom of the bowl.)
In the same bowl, blend the flour, oats, brown sugar, butter and salt, blending with a fork or your fingers until well-blended and crumbly.
Scatter over the fruit, squeezing to create larger clumps of crumble as you go.
Bake for 45-60 minutes, until the topping is golden and the fruit is soft and bubbly around the edges.
Serve warm, with ice cream or whipped cream.