Sugar Cookie Bars with Peppermint Frosting

Prepare a 9x13-inch cake pan with parchment, leaving overhang on all four sides. Preheat oven to 350°F.
In a large bowl or stand mixer, cream together butter and granulated sugar. Mix in one egg at a time, followed by vanilla, salt and baking powder. Add spoonfuls of flour at a time, increasing the speed and mixing until no streaks remain.
Lightly grease your hands with baking spray or butter. Press and spread cookie dough batter into prepared pan.
Bake at 350°F for 25-30 minutes. Cool in the pan, on a wire rack.
When the bars have cooled completely, prepare your frosting. In a large bowl or stand mixer, beat butter. Mix in peppermint and vanilla extract, followed by spoonfuls of powdered sugar at a time. Increase speed between additions. Lastly, mix in heavy cream until desired consistency is reached.
Remove cookie bars from pan and parchment paper to a cutting board or serving platter. Using a small offset spatula, spread frosting in an even layer over cooled cookie bars. Optionally, sprinkle with crushed candy canes.
Store in an airtight container for up to a week.