Prepare grill for high, indirect heat (for a charcoal grill, bank coals on 1 side of grill; for a gas grill, leave 1 or 2 burners off).
Place chicken on work surface, skin side up. Using your palms, press firmly on breastbone to flatten breast.
Rub chicken with oil; season with salt and pepper. Tuck wings slightly under breast.
Place chicken, skin side down, over indirect heat, set bricks on top, and grill, covered, until skin is golden and crisp, 25-30 minutes. Using tongs, remove bricks; turn chicken, skin side up. Replace bricks and continue grilling until chicken is cooked through and an instant-read thermometer inserted into the thickest part of thigh registers 165°F, 25-30 minutes longer.
Using kitchen shears, cut chicken along both sides of backbone to remove it. Flip chicken over. Press down on the breastbone until you hear it crack. Too chicken? Ask your butcher to do it for you.
