Preheat the oven to 190c/gas mark 5.
Roll out the pastry thinly and cut out a 32cm round disc.
Place on a greased and floured Pyrex baking sheet
Grate the marzipan and scatter over the pastry round.
Slice the pears and arrange over the marzipan.
Fold over the edges of the pastry to form a raised edge.
Brush the pastry with a little beaten egg and sprinkle over the sugar.
Bake for 15-20 minutes then scatter over the blackberries and almonds and bake for a further 10 minutes or until the pastry is golden and crisp.
Cut into wedges and serve warm with Devon clotted cream.