Step 1

Melt butter in small saucepan over medium-high heat. Add cilantro and garlic; cook until garlic begins to brown, about 2 minutes. Add piri-piri sauce and lemon juice. Reduce heat to medium-low; simmer 2 minutes. DO AHEAD Glaze can be made up to 1 day ahead. Cover and chill. Rewarm before using.

Step 2

Finely chop cilantro, ginger, shallot, and garlic in processor. Add piri-piri sauce, 1/4 cup oil, lemon juice, coarse salt, and pepper; process marinade to blend.

Step 3

Place chicken, skin side up, on work surface. Using palm of hand, press on breastbone to flatten chicken. Tuck wing tips under. Pour half of marinade into 11x7x2-inch glass baking dish. Open chicken like book; place skin side down in single layer in dish. Pour remaining marinade over. Cover; chill at least 4 hours or overnight, turning chicken occasionally.

Step 4

Remove top rack from barbecue. Prepare barbecue (medium heat). If using 2-burner gas grill, light 1 burner. If using 3-burner gas grill, do not light center burner. If using charcoal grill, light briquettes in chimney and pour onto 1 side of lower grill rack. Place disposable aluminum pan on unlit part of grill. Place upper grill rack on barbecue; brush with oil.

Step 5

Remove chicken from marinade. Arrange skin side up on grill rack above drip pan. Cover barbecue; grill until skin is browned and instant-read thermometer inserted into thickest part of thigh registers 165°F, turning often, about 40 minutes. Transfer to platter. Pour warm glaze over.