For the base: Preheat the oven to 180C/160C Fan/Gas Mark 4. Then blitz the biscuits in a food processor until fine crumbs. Then pour in the melted butter and blitz again until the mixture clumps together. Pour this into a 9inch pie tin and using a spoon, evenly press the mixture down and up the sides. Bake for 10 minutes, then set aside.
For the puree: Peel, core and chop the apples into small chunks and place into a saucepan. Then add the butter, water, caster sugar, cinnamon stick, lemon juice and stir to combine. Place over a medium heat and cook, stirring frequently, breaking up the apples as they start to soften. Keep cooking until the apples start to caramelise, then take off the heat. Discard the cinnamon stick, then mash the apples until they are completely broken down. Then pour into a bowl and set aside.
For the filling: Place the lemon juice into a medium bowl. Then using either a mandolin or a sharp knife, finely slice the apples (making sure to remove the core!) and place into the bowl, coating in the lemon juice to prevent them going brown. Then pour over the brown sugar and cinnamon, and toss together so the apple slices are evenly coated.
To assemble: Spread the slightly cooled puree on the base of the tart and slightly up the sides. Then starting from the outside, place the apples slices with the skin side on top in circles, making sure to overlap each slice. Keep going until you reach the middle, and roll one slice to create the centre, Fill in gaps with any remaining apple slices, you want it to be tightly packed. Then dot over the butter, and place in the oven for 40 minutes. The apples will feel tender and the filling will be bubbling.
With the tart out of the oven, make the glaze by heating the apricot jam and water in a saucepan over a low heat. Once the jam has loosened, use a pastry brush to carefully glaze over the apple slices.
Tart is best served warm. Can be kept in an air-tight container in the fridge for 1-2 days.
Keyword apple, apple tart, biscoff, biscuit base, cinnamon, spiced apple