Brandon Pettit made this for a special dinner at Delancey, I replicated it.

Saute 1 sweet or yellow onion, 5 cloves of garlic, minced or pressed, in 3T melted butter and 1-2 T olive oil, until soft. Let cool. Drain 2 cans/3-4 cups black cerignola, or regular black olives. Combine all ingredients, grind some black pepper on top, and puree with a stick blender until well-combined. Taste, and adjust seasonings. This freezes well, and also keeps in the refrigerator for at least 5 days.