Scapes are garlic shoots often found at farmers' markets in midsummer. Thin young scallions can be used if scapes are unavailable. If you prefer, you can toast the rolls under the broiler.
Heat grill to medium-high. Place rolls, cut sides down, on the grill; toast until golden brown. Spread with butter. Scatter the scapes and chives on top of each, and season with salt and pepper.