Cranberry Bean Ragout with Olive-Citrus Butter

From Keys to the Kitchen by Aida Mollenkamp.
Ingredients:
Olive-Citrus Butter:
1/2 c. unsalted butter, at room temperature
1/3 c. minced pitted black olives
2 tsp. grated lemon or orange zest
Cranberry Beans:
1 1/2 c. dried cranberry or white beans
4 garlic cloves, smashed
1 bay leaf
1/4 tsp. black peppercorns
8 c. low sodium vegetable broth
Ragout:
2 Tbsp. unsalted butter
1 leek, trimmed, halved lengthwise and thinly sliced
1 carrot, minced
1 celery stalk, minced
4 garlic cloves, thinly sliced
2 Tbsp. roughly chopped fresh oregano leaves (or 2 tsp. dried), plus more for garnish
One 3 in. cinnamon stick
3 Tbsp. tomato paste
Pinch of saffron threads (optional)
3 c. reserved bean cooking liquid
Kosher salt
2 to 3 Tbsp. red wine vinegar
Roughly chopped fresh Italian parsley, for garnish (optional)

For the butter:
Using a spatula, beat the butter in a large mixing bowl until very spreadable. Add the olives and zest and stir to combine; place in a small bowl or crock, cover, and refrigerate until ready to use.
For the beans:
Place the beans in large bowl. Add enough water to cover by 3 in.; soak at room temperature at least 8 hours or overnight.
Drain the beans. Wrap the garlic, bay leaf, and peppercorns with a leek leaf and tie with kitchen twine to secure. Add the beans and broth to a large pot and bring to boil. Decrease the heat to a simmer and cook until the beans are tender but still hold their shape, stirring occasionally, 45 minutes to 1 hour. Drain, reserving 3 cups of the cooking liquid. Discared the leek packet.
For the ragout:
Melt the butter in the pot used to cook the beans over medium heat. Add the leeks and cook until translucent, about 4 minutes. Add the carrot, celery, and garlic and cook until just softened. Add the oregano and cinnamon and cook until fragrant, about 30 seconds. Stir in the tomato paste and cook until fragrant.
Add the drained beans, saffron, and the 3 cups reserved cooking liquid and simmer until the beans are tender and flavors are melded together, 40 to 45 minutes. Season with salt, add 2 tablespoons vinegar, and let cook another 5 minutes. Taste and add more vinegar, as desired, to brighten the flavor of the beans. Serve topped with olive butter and herbs, as desired.
Note: The butter can be made up to 1 month ahead and stored tightly wrapped in the freezer. The beans can be cooked up to 2 days ahead.
Yield: 8 to 10 servings.