white bean and asparagus salad

1 lb medium asparagus, trimmed
1/4 c extra-virgin olive oil
1/2 t finely grated fresh lemon zest
2 T fresh lemon juice
1/2 t salt
1/4 t black pepper
2 (15-19oz) cans white beans, drained and rinsed well (3 - 3 1/2 cups)
4 slices country bread
1/2 c shaved parmesan
1/4 c chopped fresh flat-leaf parsley
2 T unsalted butter, softened
1 garlic clove, halved crosswise

Cut asparagus on a diagonal into 1/8-inch thick slices. Bring oil, lemon zest, juice, salt, and pepper to a simmer in a 4-quart heavy saucepan, then stir in beans and asparagus. Remove from heat and let stand, uncovered, 10 minutes. While beans stand, toast bread until golden. Add cheese shavings to beans along with parsley, then toss.

Spread hot toast with butter and rub buttered side of each with cut side of garlic clove, then season with salt and halve. Serve bean salad with toasts.