Grease a muffin pan and preheat oven to 180 degrees celcius. Place the flour, milk, oil, eggs, salt and stock in the Thermomix bowl and combine on speed 4 for approximately 20 seconds. Add the feta, spinach and pumpkin and mix speed 4, "Counter-clockwise operation" for 20 seconds. Spoon mixture into muffin pan and bake for 20 minutes or until muffins spring back. Leave to cool for 10 minutes before transferring to a wire rack.