Sprinkle chopped almonds into a well-greased 10-inch Bundt pan; set aside.
Cream butter and shortening; gradually add 1/2 cup each sugar and Splenda, beating well at medium speed of an electric mixer. Add egg yolks, and beat well. Add lemon rind, juice, and flavorings; beat well.
Combine flour, baking powder, soda, and salt. Add to creamed mixture alternately with milk, beginning and ending with flour mixture. Mix after each addition; set batter aside.
Beat egg whites and cream of tartar until foamy. Gradually add 1/4 cup sugar, beating until stiff peaks form; fold egg white mixture into batter. Pour batter into prepared pan. Press whole almond just below surface of batter.
Bake at 300 degrees for 1 hour and 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes; remove from pan, and let cool completely on a wire 10-inch cake.