Preheat the oven to 350 degrees. Beat the butter and brown sugar with electric mixers until creamy.

Add the cinnamon, salt, baking soda, and flour. The mixture should be crumbly. Set aside one cup of the mixture; press the rest into a 9?13 baking sheet lined with parchment paper. Bake for 12 minutes.

Quarter the apples and scoop out seeds/core. Slice the apple quarters with a mandoline slicer or slice by hand as thinly as possible.

Melt the butter in a saucepan. Add both types of sugar; when the sugar is incorporated and the mixture is just about to start bubbling, add the cream and stir until a creamy sauce forms.

When the crust is done, arrange the apples in an even layer over the crust and pour the caramel over the top.

Sprinkle with remaining crust crumbles from step one and turbinado sugar. Bake for 30-35 minutes.

Remove from oven, lift out of the pan using the edges of the parchment paper, and allow to cool for 10-15 minutes. Cut and serve.