Melt butter in a small saucepan over medium-high heat.

Add chopped cilantro and minced garlic to the melted butter.

Cook until the garlic begins to brown, approximately 2 minutes.

Add piri-piri sauce and lemon juice to the saucepan.

Reduce heat to medium-low and simmer for 2 minutes.

Finely chop cilantro, ginger, shallot, and garlic in a food processor.

Add piri-piri sauce, olive oil, lemon juice, coarse salt, and pepper to the processor and blend.

Place chicken, skin side up, on a work surface.

Press on the breastbone to flatten the chicken.

Tuck the wing tips under the chicken.

Pour half of the marinade into a baking dish.

Open the chicken like a book and place skin side down in the dish.

Pour remaining marinade over the chicken.

Cover and chill for at least 4 hours, or overnight, turning occasionally.

Remove the top rack from the barbecue.

Prepare barbecue for medium heat. If using a gas grill, light one burner (or two outside burners on a 3-burner grill). If using a charcoal grill, light briquettes and pour onto one side.

Place a disposable aluminum pan on the unlit part of the grill.

Place the upper grill rack on the barbecue and brush with oil.

Remove chicken from the marinade.

Arrange chicken skin side up on the grill rack above the drip pan.

Cover the barbecue and grill until the skin is browned and an instant-read thermometer inserted into the thickest part of the thigh registers 165°F, turning often, approximately 40 minutes.

Transfer the chicken to a platter.

Pour warm glaze over the chicken.