Heat the oil in a large pan over a medium-low heat. Add the onion and carrot and cook, stirring occasionally, for 7-10 minutes, until softened.
Increase the heat to medium, add the beef mince and brown for 3 minutes, breaking it up with a wooden spoon.
Add the squash, vegetable stock, chopped tomatoes and Worcestershire sauce and bring to the boil. Reduce the heat to low, cover, and simmer for about 15 minutes, until the squash is tender. Stir in the beans and spinach and heat through.
Meanwhile, draw a bat shape on a piece of greaseproof paper and cut out. Remove the crusts from the bread, then roll out each slice using a rolling pin. Place the stencil over the bread slices one at a time, and cut around the stencil using scissors. Toast each side until golden.
To serve, ladle the stew into a washed hollowed-out pumpkin or serving dish. Top with the bat-shaped croûtons for mopping up the juices.