First - make sure you have a good verity of apples - the crumble will taste better. Peel them and slice thinly. Use the lemon and squirt all over the apples to prevent them from turning brown while you make the topping and the caramel.
To make the crumble topping - mix in the flour, 1 cup of sugar, the cinnamon, 1/2 the salt, the allspice, the nutmeg, the oats, and the pecans. Mix together well. Then, using a pastry cutter, or a fork in a very large bowl, cut in 1 cup of the butter. The topping should look crumbly.
In a cast iron skillet, melt the remaining butter (1/2 cup) and the remaining sugar (1 cup). On medium for about 7 minutes you'll start to have a caramel...it's so yummy!! Add in all of your apples - or all that will fit. Stir around gently and try and coat all the apples in the caramel. After about 4 minutes of stirring, remove from the heat and put the crumble topping on top. Pile it on!
Bake right in the cast iron skillet at 375 degrees for about 20-25 minutes. Longer if you want the top really crispy.
Let it cool for about 10 minutes. It smells so good - like a fall afternoon in 1958.
Serve up with some vanilla ice cream and you're all set.
Enjoy the yumminess of skillet apple crumble.