Heat 1 tablespoon of olive oil in a pan over medium heat. Add the minced garlic and cook for 1 minute until fragrant but not browned.
Add the drained butter beans and thyme. Stir and cook for 2-3 minutes to warm through.
Tip the beans into a bowl. Add the remaining olive oil, lemon zest, lemon juice, salt and pepper.
Mash with a potato masher or fork until you get a rough, creamy texture. Add the warm water to loosen if needed.
Taste and adjust seasoning. Top with chopped parsley if using.
Serve warm as a side dish or on toast as a main.