Creamy Cauliflower Soup


1 tbsp. olive oil
1 large onion, peeled and chopped
1 regular head of cauliflower, outer leaves discard, chopped into small florets
500ml hot vegetable or chicken stock (either homemade or use 2 stock cubes with water. Use bouillon for gluten free)
¼ tsp garlic salt
100g mature cheddar
50ml double cream
Salt and pepper to taste