Preheat and prep:
Set your oven to 180°C (Fan) / 350°F / Gas Mark 4 so it’s ready when you are.

Make the crumble topping:
In a medium-sized bowl, whisk the flour and light brown sugar together.
Add in the butter, cut into cubes, and use your fingertips to rub it in until you’ve got a crumbly, sandy texture — like coarse breadcrumbs. (You can also pulse everything in a food processor if you’d rather keep your hands clean.)
Stir in the crushed Biscoff biscuits for that extra caramel crunch.

Prepare the apple filling:
Drizzle the lemon juice into a mixing bowl. As you peel and chop your apples, toss them straight into the bowl and stir to coat them in the juice. This little trick keeps the apples from turning brown while you work.
Sprinkle in the sugar, cornflour, cinnamon, and mixed spice, then give everything a good mix until the apples are evenly coated in that sweet, spiced goodness.

Assemble the crumble:
Spread your apple mixture evenly into a baking dish (around 2.2L or similar size).
Drop spoonfuls of Biscoff spread across the apples — those pockets of caramel magic will melt into gooey bliss while baking.
Scatter your prepared crumble mixture evenly over the top, covering all the apples.

Bake it up:
Slide the dish into your preheated oven and bake for about 40 minutes, or until the topping is golden brown and you can see the filling bubbling around the edges.

Serve and enjoy:
Serve warm, ideally straight out of the oven, with a generous pour of custard, a dollop of cream, or a scoop of vanilla ice cream — your call!