Preheat oven to 350 degrees. Grease and flour a 9-inch square pan.
Melt 1/2 cup butter. Remove from heat and stir in sugar, eggs and 1 teaspoon vanilla. Gently stir in 1/3 cup cocoa, 1/2 cup flour, salt and baking powder. Spread batter into prepared pan.
Bake in preheated oven for 28-30 minutes. Remove from oven and sprinkle with crushed candy canes. Cool for at least 15 minutes before cutting.