• Preheat the oven to 350°F(177C°). Grease 8 inch (20cm) square oven-proof dish and line the bottom and sides with parchment paper, about 2 inches(5 cm) of overhang on each side.
  

Apple Filling

• Peel, core and slice the apples into small pieces.  Place the chopped apples into a medium bowl.  Toss the apples with lemon juice, sugar, flour/cornstarch, cinnamon and nutmeg. Set aside the bowl.  

Crust & Crumbles

• Combine flour, cinnamon, and sugar in a large bowl.  
• Add the cold cubed butter and cover with flour mixture so you can cut the butter into the flour mixture easily.  You can use 2 forks or a pastry blender. Alternatively, you can rub with your fingertips.

Assemble

• Spread ⅔ of the mixture into the oven-proof dish with a spoon.  Lightly flour the spoon to avoid it sticking to the flour-butter mixture. You can spread with your hand too.  Add the apple mixture over the dough and cover the apples with the remaining ⅓ dough. You can make some big crumbles by squeezing the dough with your hand.  
• Bake for 55 minutes until the top becomes golden brown and the crumbles are crunchy. Let it cool completely before slicing.  You can let it cool at room temperature for 1-1,5 hours and then you can keep in the freezer so it can cool faster.  Once completely cool, lift the paper from the sides, remove the bars from the dish, cut into 16 pieces.  You can keep in the fridge in an airtight container up to 4 days or freeze up to 3 months.