In the bowl of a stand mixer fitted with the paddle attachment, add all ingredients and mix on low speed until a smooth dough forms and no visible butter remains. Set aside. You can make this up to a week ahead of time and refrigerate.
Can also be made by squeezing the butter into the ingredients by hand.
Prepare your Filling:
Peal and core apples. I like to slice each half into quarters lengthwise before slicing, which will ensure the filling cooks through before the topping burns. Then slice each apple section in to thin slices about 1/8 inch thick. Place in a large bowl.
Zest lemons over apples then cut in half and squeeze juice over apples, catching any seeds that fall.
Add dark brown sugar, granulated sugar and butter. Stir to coat apples.
Assemble & Bake:
Pour apples into a baking dish. I used a 9 inch oval Le Creuset casserole dish but a 9”x11” baking dish or large cast iron pan will work as well.
Squeezing the topping together to create clumps, add the topping all over the apples to cover completely. I like to have some small and some large clusters.
Bake in preheated oven 45-60 minutes until the topping is golden brown and the filling is bubbling in the center. If the topping starts to get too dark, then tent it with some aluminum foil, just remove for the last 10 minutes of baking to crisp it back up!
Cool and serve!
Notes
This makes one large apple crisp. It can be made up to a week in advance. Keep tightly wrapped and refrigerated.