1Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom only of 13x9-inch pan with baking spray with flour. In large bowl, beat all cake ingredients except carrots with electric mixer on low speed 30 seconds, then on medium speed 2 minutes. Stir in carrots. Pour into pan.
2Bake 44 to 50 minutes (46 to 54 minutes for dark or nonstick pan) or until toothpick inserted in center comes out clean. Cool completely, about 1 1/2 hours.
3In large bowl, beat powdered sugar, cream cheese, 2 tablespoons butter and the vanilla on low speed until blended. Beat on medium speed until smooth and creamy. Spread frosting over cake. With knife tip, score cake into 5 rows by 3 rows (15 squares).
4Diagonally on each marked cake piece, sprinkle a small amount of crushed cookies for "dirt." Insert carrot decoration into each piece. Refrigerate 30 minutes before serving. Store covered in refrigerator.