Preheat the oven to 350 degrees. Line a 9″x13″ pan with foil and coat with cooking spray.
Place the butter and chocolate chips into a large bowl. Melt in microwave – heat for 30-second intervals and stir between each interval until butter and chocolate are melted and thoroughly combined.
Stir in the sugar, then stir in the eggs, one at a time, whisking until smooth after each addition.
Stir in the vanilla extract. Gently fold in the salt and flour.
Pour the batter into the prepared pan and bake for 25-30 minutes or until a toothpick inserted into the brownies comes out clean.
Cool the brownies to room temperature, then chill for at least 30 minutes.
Using the edges of the foil, remove the slab of brownie from the pan. Using a sharp knife, cut the brownies into 16 triangles.
Snap the curved parts off the candy canes and insert the straight parts of the candy canes into the bottom of the brownies.
Place the frosting in a piping bag fitted with a plain or star tip, or resealable plastic bag with the tip snipped off. Pipe approximately 1 1/2 tablespoons of frosting onto each brownie.
Place a star sprinkle at the top of each brownie, then add rainbow sprinkles all over each brownie.
Serve, or store, covered, in the refrigerator for up to one day.