Cook bacon in microwave on a paper towel-lined plate. Cover with paper towels and cook 3-5 minutes, until crispy. Cool, crumble and set aside.
Cook chopped onions in the microwave for 3 minutes until soft.
Heat olive oil in a large pot or pan over medium heat. Add garlic and cooked onion. Cook together stirring frequently for 2 minutes. Stir in chicken broth and potatoes; bring to a boil. Turn down to simmer, cover, and cook about 10 minutes until potatoes are soft.
In the meantime, in a small bowl, add milk. Stir in cornstarch using a whisk or fork until well combined. Using a rubber spatula or wooden spoon, so potatoes don’t break, stir in sausage pieces, spinach and milk. Add black pepper to taste. Bring up to a boil, turn down to simmer, and cook for 5 minutes uncovered.
To Serve: Ladle 1½ cups into each bowl. Garnish each bowl with about ½ tablespoon of crumbled bacon and serve.