Preheat the oven to 400°F. Brush the slices of bread with a tablespoon of the olive oil and place them on a baking sheet. Toast, turning once, until just golden, about 6 to 8 minutes.
Meanwhile, in the bowl of a food processor, combine the beans, rosemary, and remaining 3 tablespoons olive oil and puree until smooth. Season with the salt and pepper.
Spread the puree on the toasts or serve as a dip surrounded by the toasts.