Gather your crust ingredients. Beat together softened butter and sugar. In a small pot you can put your bowl over, get a small amount of water barely simmering, put the bowl on top of the pot (water not touching the bowl) and beat egg into butter and sugar for a few minutes until it emulsifies into a glossy smooth mixture.
Take off heat and cut in flour gently with a spatula until it just incorporates into a ball. Form into a flattened disc and cover with siran wrap. Refrigerate for at least 45 minutes.
Put a large pot on medium heat and add the butter and brown sugar and mix together. Once the butter sugar mixture starts bubbling, add half the apples. Mix the apples frequently on medium to medium-high heat for about 15 minutes until they cook down to mush and there's very little liquid left in the pot.
Add the remaining apples and cook for another 10 to 15 minutes until the apples are tender and the liquid has cooked out. Take off the heat and mix in the vanilla. Set aside and let cool.
Combine the flour, butter, and brown sugar for crumble topping in a large bowl. Incorporate using hands until everything is combined and you're left with a nice crumbly mix.
Preheat oven to 375°F. Take the crust out of the refrigerator and put on a lightly floured surface to roll out. With a rolling pin, roll out the dough and rotate it a bit after every roll so it doesn't stick to the counter. It should be rolled out to about 1/4 inch thick.
Grease a 9-Inch springform or tart tin and mold crust into it. Put rolling pin over top to cut off the extra bits. Prick all over the bottom of the crust with a fork. Then add in filling. Put crumbles on top. Bake for about 30-40 minutes. Wait until its completely cool to take out of tin. Enjoy!