• 8 Tbsp. (1 stick) unsalted butter , slightly softened
• 1 thinly sliced onion
• 3 1/2 Tbsp. capers (preferably salted), rinsed
• 1/2 cup vin santo or tawny port (dessert wine)
• 2 cans (15 ounces apiece) chickpeas , drained
• 1 tsp. white truffle oil
• Sea salt and freshly ground pepper

Melt half of butter in a medium sauté pan over medium-low heat. Add onion and cook, stirring occasionally, until well caramelized, about 45 minutes. Add capers and vin santo, and stir to loosen the browned bits on the bottom of the pan. Continue to cook until the liquid has reduced by half, 2 to 3 minutes. Remove from heat and allow mixture to cool completely (about 1 hour).

Transfer to a food processor and add chickpeas and truffle oil. Puree into a paste. Add remaining butter and puree until smooth. Season to taste with salt and pepper.

Mound puree in a serving bowl and chill for at least 2 hours (up to 24 hours). To serve, spread on toasted brioche.