PREHEAT oven to 350°F/180°C. TOSS the diced pumpkin with 1 tablespoon of olive oil, place in a single layer on a baking tray and cook for 15 minutes. WHILE the pumpkin bakes, heat 2 tablespoons of olive oil in a frying pan over a medium heat. COOK the onion for 6 minutes, then add the spinach and cook for 4 minutes, stirring regularly. STIR in the dill, salt and pepper and remove from the heat. STIR in the crumbled feta and baked pumpkin (keep the oven heated to 350°F/180°C) and set aside. COMBINE the remaining 2 tablespoons of olive oil with the melted butter in a small bowl. PLACE 2 phyllo sheets side-by-side on a work surface and brush each sheet evenly with the butter-oil mix. Place 2 more sheets on top and brush with butter-oil, then repeat once more. CUT each stack into six 5-inch (12.5 cm) squares, for a total of 12 stacks with 3 sheets each. LIGHTLY grease a standard 12-cup muffin pan with the butter-oil mix. PLACE each square phyllo stack into a muffin cup, pressing gently to mould the pastry into the bottom. SPOON ¼ cup of the spinach-pumpkin filling into each and fold the extra pastry back over the filling, roughly crumpling around the edges so that the filling is still exposed. BRUSH the edges with the remaining butter-oil mix. SPRINKLE pine nuts in the middle of each tart. BAKE for 22 minutes, then remove from the oven, and transfer the tarts from the muffin pan to a cooling rack. LET cool slightly then serve.