Rinse your dried white beans under cold water and pick through them quickly for any rocks (I know that sounds dramatic but it happens). Add them to a large pot and cover with 6 cups of water. Bring everything to a boil, then reduce heat and simmer for about 1 hour until the beans are tender but not falling apart. Drain and set aside—this is the secret step that makes your white bean soup recipe taste restaurant-quality.
Heat olive oil in the same pot over medium-high heat. Dice your onion and add it to the pot, stirring constantly for about 3 minutes until it gets soft and starts turning golden. Mince your garlic and throw it in, cooking for another 30 seconds until the kitchen smells amazing. Don't walk away here or the garlic will burn and taste bitter.
Add your sliced carrots and celery stalks to the pot. Stir everything together and let it cook for 5 minutes so the veggies start softening and getting to know each other. You want them to release their flavors into the oil before you add the liquid.
Pour in your chicken broth and add the diced potato plus the cooked beans from earlier. Sprinkle in your dried thyme, salt, and black pepper. Stir everything well and bring it to a gentle simmer—you'll hear it start bubbling around the edges. Let this simmer for about 25 minutes until the potato is completely tender when you poke it with a fork.
Here's where the magic happens: reduce the heat to low and stir in the butter and heavy cream. Do this slowly and keep stirring so everything combines smoothly without any lumps. This transforms your soup from good to absolutely creamy and restaurant-quality in literally 2 minutes.
Taste your white bean soup and adjust the salt and pepper if needed. I always add more pepper than the recipe calls for because I like that little kick, but taste and decide what works for your mouth. Simmer on low for another 10 minutes so all those flavors get cozy together.
Ladle into bowls and serve hot. Some people like to add a drizzle of olive oil on top or fresh cracked pepper—honestly both are amazing. If you're not eating it right away, let it cool to room temperature before storing (this prevents condensation from making it watery).