3 tablespoons unsalted butter, cut into small chunks, plus more for greasing the pan
3 very ripe plantains (they should appear almost completely black on the outside), peeled
1/2 cup light brown sugar
1/4 cup granulated sugar
1/2 teaspoon ground cinnamon
1/2 cup Madeira
2 cinnamon sticks
Put yellow and black-spotted plantains in a paper bag. In a couple of days they should be completely black on the outside and perfectly ripe on the inside, exactly how they are needed for this dish.