Preheat the oven to 180°C Fan.
Crush the digestive biscuits into fine crumbs using a freezer bag and rolling pin.
Stir the crumbs into melted butter and press firmly into the base and sides of a 20cm tart tin.
Chill the biscuit base in the fridge while preparing the filling.
Cream softened butter and sugar together until light and fluffy.
Mix in the beaten eggs, ground almonds, and almond extract until well combined.
Layer thinly sliced peeled apples over the chilled biscuit base.
Spread the frangipane mixture over the apples and sprinkle with flaked almonds.
Bake for 20 to 25 minutes until the tart is golden-brown and set.
Cool for 15 minutes before removing from the tin and serving warm.