Step 1

Bring beans, stock, and thyme sprigs to a gentle simmer in a medium pot over medium-high. Reduce heat to medium-low and simmer, partially covered, skimming any foam from surface, until beans are tender, 1–1½ hours, depending on types. Discard thyme. Season with kosher salt and pepper, remove from heat, and let sit 30 minutes.

Step 2

Return to a simmer; stir in cream. Season with more kosher salt and pepper if needed. Serve topped with thyme leaves and sea salt and drizzled with oil.

Step 3

Do Ahead: Beans can be cooked 3 days ahead. Let cool; cover and chill.