Sift the flour, baking powder and salt together.
Break the eggs into a mixing bowl and beat at medium speed for 5 minutes.
Add the sugar and beat for 5 minutes longer.
Beat in the hot water quickly.
Fold in the flour mixture.
Spread on a lightly greased rimmed baking sheet.
Bake at 350 degrees for 45 minutes.
Cool and cut into squares or bars.
Place the butter in a mixing bowl and beat in enough confectioners' sugar to make a stiff frosting.
Beat in the milk and vanilla.
Frost all sides of the cake pieces and roll in the ground peanuts.