Chop up 1 onion. Melt 4 TBS butter in a large heavy pot, then sauté the onion for 5 minutes.
Cut 1 bunch of Tokyo Cross Turnips into small cubes. Add to the butter along with 4 minced garlic scapes. Cook over medium heat with the lid on for 8-10 minutes, until the vegetables are golden around the edges.
Sprinkle 2 TBS flour into the pot, along with ½ tsp of dried red chili flakes (optional) and ½ tsp of turmeric. Cook for 3 minutes, then add 4 cups vegetable or chicken stock, stir well and cover.
Cook over low heat for about 20 minutes until vegetables are soft.
Pour into a blender and whiz up.
Add ½ cup cream, 2 TBS grainy mustard, sea salt and freshly ground black pepper.
Dice 4 ounces extra sharp cheddar or Gruyere into small cubes.
Put the cheese into 4 bowls, than ladle the soup over and top with some finely chopped chives and/or flat leaf parsley.