Heat the oil in a small skillet over medium heat. Add the garlic and rosemary and cook until very fragrant, being careful not to let the garlic brown. Remove from heat.
Place the beans in a small bowl. Add the oil and season to taste with the salt and pepper. Using the back of a spoon, smash the beans to form a very rough paste. Add more olive oil if necessary.
Drizzle with additional oil, sprinkle with more salt and pepper, and serve with slices of bread. (This can be made 2 to 3 days in advance and kept in the freezer for up to 2 months.)