Sift together flour and ½ cup sugar 4 times. Set aside.
In large bowl, beat egg whites until foamy.
Add salt, cream of tartar, vanilla, and almond extract. Beat until soft peaks form, but remain moist and glossy.
Add remaining 1 ½ cups sugar, sprinkling 5 tablespoons at a time over white and beating well after each addition.
Sift flour mixture over egg whites in 4 small additions, folding each in well.
Gently pour batter into ungreased 10-inch tube pan.
Bake at 375 degrees approximately 30 minutes.
Remove cake from oven. Invert pan onto neck of bottle or cooling rack. Cool 1 ½ hours.
When cake is cooled, remove it from the pan and make sure it’s positioned so the cake is wider at the bottom than at the top. Using a serrated knife, cut a horizontal slice one inch from the top of the cake, all the way around, until the top of the cake can be removed. Lay aside.
With a small paring knife, make two concentric cuts in the cake: one cut is 1 inch from the outside rim, the other cut is 1 inch from the inside rim. Be careful not to cut all the way through to the bottom of the cake.
Slice out sections of this middle ring of cake and remove to form a trench in the middle of the cake.
Whip the heavy cream and powdered sugar together until stiff. Place 1/3 of whipped cream in a bowl and stir in the almonds and butterscotch chips. Spoon into trench in cake.
Replace cake “lid”, lining up the edges to the original position.
Spread remaining whipped cream over outside of cake. Garnish with almonds on top.
For best results, chill for a few hours before serving.