Allow butter and eggs to stand at room temperature for 30 minutes. Preheat oven to 325 degree F. Grease and flour a 10-inch fluted tube pan; set aside. Stir together flour and baking powder. In a large mixing bowl beat butter with an electric mixer on medium speed for 30 seconds. Gradually add sugar to butter, about 2 tablespoons at a time, beating on medium to high speed about 6 minutes total or until very light and fluffy. Add vanilla and almond extract.
Add eggs, one at a time, beating 1 minute after each, scraping bowl often. Gradually add flour mixture, beating on low to medium speed just until combined. Fold in the finely chopped mango. Pour into the prepared fluted tube pan.
Bake in a 325 degree F oven for 60 to 65 minutes or until a wooden toothpick inserted near center comes out clean. Cool on rack for 10 minutes; remove from pan. Cool thoroughly on wire rack.
For glaze, in a small mixing bowl stir together powdered sugar and enough of the mango nectar or orange juice to make of drizzling consistency. Spoon glaze over cooled cake, allowing it to drizzle down sides. Serve cake with mango slices. Makes 16 servings.