The ornamental design for a cooking platter, as shown and described.
FIG. 1 is a perspective, front view of a cooking platter showing our new design;
FIG. 2 is a bottom plan view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a left side elevation view thereof.
The figures depicting the bottom, sides and ends of the cooking platter are shown in broken lines and form no part of the claimed ornamental design; these figures are provided for completeness only. Similarly, the top edge of the cooking platter is shown in broken lines and also forms no part of the claimed ornamental design.