Ham Potato and Corn Chowder


1½ cups ham, roughly chopped (Note 1)
½ tbsp olive oil
3 tbsp butter
1 garlic clove, minced
1 small onion, diced (or half large onion) (yellow, brown or white)
2 potatoes, peeled and diced into 8mm / ⅓” cubes (Note 2)
1½ cups frozen corn (or drained canned corn)
5 tbsp flour
2 cups milk (I use low fat but full fat will work too)
1 cup chicken stock
1½ – 2 cups water
1½ tsp fresh thyme leaves (or 1 tsp dried thyme), plus extra for garnish
½ tsp salt
Black pepper