1. Preheat oven to 350°F. Grease and flour a 9×13 inch baking pan.
2. In a large bowl, combine melted butter and sugar until smooth.
3. Beat in eggs one at a time, then add vanilla and peppermint extracts.
4. In another bowl, whisk flour, cocoa, baking powder, and salt.
5. Gradually add dry ingredients to wet ingredients, mixing until just combined.
6. Stir in semi-sweet chocolate chips.
7. Pour batter into prepared pan and spread evenly.
8. Bake for 25-30 minutes, or until a toothpick comes out with moist crumbs.
9. Cool completely in pan on a wire rack.
10. Melt white chocolate chips and drizzle over brownies.
11. Sprinkle with crushed candy canes and sprinkles before the chocolate sets.
12. Cut into squares and serve.