Dried cannellini beans cook up perfectly tender thanks to a salty soak.
Day 1: Add 4 cups water and 2¼ teaspoons salt to large bowl. Use wooden spoon to stir to dissolve salt.
Place colander in sink. Add dried beans to colander. Search through beans and pick out any small stones or broken beans and discard. Rinse beans with cold water.
Add drained beans to salt water in bowl. Cover bowl with plastic wrap and let beans soak at room temperature for at least 8 hours or up to 24 hours.
In large saucepan, combine drained beans, remaining 1½ teaspoons salt, and remaining 5 cups water. (Return colander to sink for step 8.) Bring to boil over medium-high heat.
Reduce heat to medium-low and cook at gentle simmer (small bubbles should break occasionally across surface of water), stirring occasionally with wooden spoon, until beans are barely al dente (tender but still chewy in the middle), 25 to 30 minutes.
In 12-inch nonstick skillet, combine oil and garlic. Cook over medium heat until garlic begins to brown lightly at edges, 3 to 4 minutes.
Add red pepper flakes and cook for 30 seconds. Add drained cooked beans and stir gently to coat with oil. Cook, stirring occasionally, until heated through, about 2 minutes. Turn off heat. Sprinkle with parsley (if using) and serve.