Serves 10 to 12 Ingredients 9 tablespoons unsalted butter 1½ cups packed light brown sugar ¾ teaspoon ground cinnamon 6 firm-ripe bananas, peeled and cut crosswise into ¾-inch thick slices ¼ cup banana liqueur ½ cup dark rum 4 large eggs, lightly beaten 3 cups heavy cream 1 cup milk 1 teaspoon pure vanilla extract…