Heat olive oil in a skillet over medium heat. Add sliced andouille sausage and cook until browned with caramelized edges, about 5-7 minutes. Transfer to slow cooker.
Add diced potatoes, onion, bell pepper, carrots, celery, and minced garlic to the slow cooker.
Pour in chicken broth. Add Cajun seasoning, salt, and black pepper. Stir to combine all ingredients.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until potatoes are fork-tender.
About 30 minutes before serving, use a potato masher to mash potatoes 8-10 times in the slow cooker, leaving visible chunks for texture.
Stir in milk and whipping cream. Continue cooking for 20-30 minutes until heated through.
Add shredded cheddar cheese and stir until melted and incorporated.
Taste and adjust seasoning. Add Tabasco sauce 1/4 teaspoon at a time for extra heat if desired.
Ladle soup into bowls and garnish with sliced green onions. Serve hot.
Notes
You’ll need a 6-quart slow cooker for this recipe.
Andouille sausage provides authentic Cajun flavor. Turkey andouille works for a lighter option.
Brown sausage first for deeper flavor development.
Mash some potatoes to naturally thicken the soup without adding flour.
Adjust Cajun seasoning and Tabasco to control heat level based on your preference.
Allow soup to cool 30 minutes before storing in airtight containers.
Can be frozen for up to 2 months. Thaw overnight in refrigerator before reheating.