Something easy to do if you have leftover ingredients –
Defrost a sheet of flaky puff pastry, cut it into circles, and layer the pastry between your ingredients. Top with a slightly larger circle and seal the edges. Brush with egg wash. Bake at 200°C for about 20-30 minutes, until golden brown.
I used leftover butternut squash filling, some roasted potatoes cut into cubes, and grated cheese for mine.