Place your margarine 20 minutes into a freezer before making the pastry. For the pastry, place the dry ingredients into a mixing bowl together with the margarine and rub with your fingertips into fine breadcrumbs. Gradually mix in the water and knead into a soft pliable dough. Cover with plastic and allow rest in a refrigerator. Meanwhile, prepare the filling. Place a knob of margarine in a hot pan and shallow fry the spring onion and spinach till wilted. Take off the heat, stir in the pumpkin and remaining ingredients. To make the Empanadas, lightly dust a flat surface and roll out the pastry into a 5 cm thick cigar. Divide the pastry into 10 pieces, flatten with a rolling pin into 2 mm thick disks, damp the edges with water, spoon filling in centre and turn over to close the empanadas. Transfer on a baking tray lined with baking paper and baked in a preheated oven at 180°C. Bake till golden brown and brush with extra margarine as soon as they come out of the oven.