In a large saucepan cook onion, garlic, salt, and pepper in hot oil over medium heat for 3 to 4 minutes or until onion is tender. Add 3 cups of the chicken stock and the potatoes. Bring to boiling; reduce heat. Cover and simmer for 15 to 20 minutes or until potatoes are tender.
Meanwhile, in a food processor or blender combine half of the spinach, rosemary, and ½ cup of the remaining stock. Cover and process or blend until smooth. Add blended spinach mixture to the saucepan. Repeat with remaining spinach, rosemary, and ½ cup stock; add to saucepan. Whisk yogurt into mixture in saucepan until combined. Stir in ham and heat through (do not boil). Ladle into bowls and top each serving with almonds.
Tip: If heirloom potatoes are popping up at the farmers market, try some other waxy potato varieties, such as fingerling, creamer ruby gold, and creamer yellow Dutch. Avoid starchy russets, which will fall apart during cooking.