What, no potato? Substituting potato with home grown pumpkin in my Chicken and Leek Cobbler

I recently went to make a favourite dinner of mine...Chicken and Leek Cobbler...only to discover there were no potatoes in the pantry. However, I still had some of my home grown pumpkins that needed using up. So I had a go at substituting potato for pumpkin, with great results. Here is the recipe. 50g butter; 1kg free range chicken breast fillets, cut into strips; 1 large leek, trimmed and finely sliced (I used home grown leeks); 1 stick celery, finely sliced; 1 tablespoon plain flour; 1 cup chicken stock; 1 cup cream; 3 teaspoons Dijon mustard (although I actually used Beerenbergs Bavarian Mustard which is lovely). Topping - 400g potatoes or equivalent in pumpkin; 1 1/3 cups self raising flour; 1/2 teaspoon salt; 1/4 cup grated mature Cheddar; 100g cold butter, chopped; 1 egg yolk, lightly beatedn to glaze. Melt half the butter in a pan. Add the chicken and cook until golden. Remove from pan. Add remaining butter and cook the leek and celery until soft. Return the chicken to the pan. Sprinkle flour over chicken mixture and stir for 1 min. Remove from heat and stir in stock and cream. Mix well to avoid lumps. Return to heat and bring to boil, then reduce heat and simmer for about 20 mins. Add mustard and season with salt and pepper to taste. Transfer mixture to 1.25 - 1.5L casserole dish. Preheat oven to 200 degrees celcius. To make the topping, steam or boil pumpkin until tender. Drain and mash until smooth. Place flour and salt in food processor and add cheese and butter. Process in short bursts until mixture is like breadcrumbs. Add this to pumpkin. If mixture is too sloppy, add more flour (pumpkin tends to be more moist than potato). I added rice flour which gave the end result a lovely texture. Bring together with your hands to form a dough. Roll dough onto floured board and roll out until 1cm thick. Use a scone cutter to cut circles into it.Keep rerolling pastry and cutting circles until all pastry is used up. Carefully lay the circles over the chicken and leek filling, overlapping the circles. Brush the dough circles with egg yolk with a little milk mixed in if needed. Bake about 30 mins or until dough is golden. Absolutely delicious! This recipe is adapted from Family Circles Step by Step Quiches, Pies and Tarts