Preheat the oven to 200°C, fan 180°C, gas 6. Put a baking sheet in the oven to heat up.
Roll out 375g of the pastry and use it to line a 1-litre pie dish, trimming any excess pastry with a knife.
Mix together the frozen cherries, ground almonds and 3 tbsp of the caster sugar, and tip into the pastry-lined pie dish.
Roll out the remaining pastry and cut into long strips. Weave the strips together over the pie filling to form a lattice pattern. Press down the edges to seal and trim off any excess pastry. Brush the lattice with the beaten egg glaze and sprinkle over the rest of the sugar.
Transfer the pie to the hot baking sheet and bake for 45-50 minutes until the pastry is crisp and golden.