Preheat oven to 350°F. Stir 6 tablespoons butter, brown sugar and honey in heavy medium skillet over low heat until butter melts and sugar and honey blend in, forming thick, smooth sauce. Transfer to 9-inch-diameter cake pan with 2-inch-high sides. Arrange plums on top of the butter-y mixture.

Mix flour, baking powder, cinnamon and salt in medium bowl. Using electric mixer, beat remaining 6 tablespoons butter in large bowl until light. Add sugar and beat until creamy. Add eggs and beat until light and fluffy. Beat in extracts. Add dry ingredients alternately with milk, mixing just until blended. Spoon batter evenly over plums. Bake cake until golden and tester inserted into center of cake comes out clean, about 1 hour 5 minutes. Transfer to rack; cool in pan 30 minutes.

Using knife, cut around pan sides to loosen cake. Place platter atop cake pan. Invert cake; place platter on work surface. Let stand 5 minutes. Gently lift off pan. Serve cake warm with vanilla ice cream or whipped cream.