The ornamental design for a birthdaycakeprotectiveenclosure, as shown and described.
FIG. 1 is a perspective view thereof, the broken line disclosure representing a plurality of candles and a cake being for illustrative purposes only forming no part of the claimed design;
FIG. 2 is a top view thereof, the broken line disclosure representing a plurality of candles and a cake being for illustrative purposes only forming no part of the claimed design; and,
FIG. 3 is a side view thereof, the broken line disclosure representing a plurality of candles and a cake being for illustrative purposes only forming no part of the claimed design.