Preheat your oven to a warm 200C (180C using a fan oven) or Gas Mark 6 to ensure even baking. Place the digestive biscuits into a large re-sealable freezer bag. Using a rolling pin, bash them thoroughly into fine, sandy crumbs—this will form the buttery crust. Melt the butter gently in a small saucepan, then pour it over the biscuit crumbs. Stir well so every crumb is deliciously coated in butter. Tip this mixture into your tart tin. Using the back of a spoon, press the crumb mix firmly and evenly across the base and up the sides of the tin to create a sturdy and smooth shell. Pop this into the fridge to chill and set while you prepare the filling. In a bowl, cream together the 75g salted butter and caster sugar until the mixture becomes light and fluffy—about 2 to 3 minutes. For convenience, a food processor can speed up this step. Gradually mix in the beaten eggs, ensuring each addition is fully incorporated before adding the next. Fold in the ground almonds and almond extract, blending gently to create a velvety frangipane mixture. Peel the Bramley apples and slice them thinly. To keep the slices looking fresh and prevent browning, slice them right before assembly. Arrange the apple slices neatly over the chilled biscuit base, covering it evenly. Spoon the frangipane filling over the apples, spreading it out smoothly with a spatula or the back of a spoon. Sprinkle the flaked almonds on top to add a lovely crunch and golden finish once baked. Bake the tart in your preheated oven for 20 to 25 minutes, or until the frangipane is set and beautifully golden brown. Once baked, remove the tart from the oven and let it cool in the tin for about 15 minutes. To remove the tart from the tin, a helpful tip is to stand the tin on a can of beans or similar sturdy object and gently push down the sides of the tin. This releases the clam shell sides cleanly, making the tart easy to transfer. Carefully slide the tart, still resting on the base of the tin, onto a serving plate. For the best experience, serve this warm with a dollop of fresh cream, crème fraîche, or a scoop of ice cream to complement its rich and fruity flavors.