Preheat oven to 400°F. Combine first 4 ingredients and egg yolks in a mixing bowl. Beat with an electric mixer until smooth. Using clean dry beaters, beat egg whites in another mixing bowl until stiff but not dry. Gently fold egg whites into ricotta mixture. Melt butter in a 10 inch ovenproof skillet over medium high heat. Add almonds and saut, 1 minute or until golden. Remove from heat. Spoon ricotta mixture evenly into skillet. Cook about 1 minute without stirring. Transfer to oven and bake 12-14 minutes or until just set. Run a spatula around edge of cake and invert onto a serving platter. Sift confectioner's sugar over cake just before serving. Garnish with mango slices.
