Preheat oven to 350 degrees and prepare 8x8 sized baking pan with parchment paper and non-stick spray.
In a medium sized bowl, add melted butter, granulated sugar and brown sugar and whisk together.
Next add in eggs one at a time, mixing after each addition to incorporate.
Mix in oil and vanilla extract.
In intervals, slowly add in flour, cocoa powder, baking soda and salt until batter is well mixed, smooth and all ingredients are well incorporated.
Add brownie batter to 8x8 sized baking pan.
Bake for 25-30 minutes or until a toothpick inserted into the center comes out just barely clean. Don't overbake.
Remove brownies and cool on cooling rack while you make the frosting.
For the Peppermint Frosting:
Add butter to stand mixer and mix on medium speed until fluffy.
Next slow down mixer to slowest speed and carefully add cocoa powder and powdered sugar to butter. Once it begins to mix in, speed the mixer up to medium speed and allow until everything is incorporated and fluffy.
Then add in vanilla extract, peppermint extract and milk and mix until completely fluffy and well incorporated.
Spread frosting over brownies then sprinkle with crushed peppermint. Cut into squares and serve.
You can easily change the flavor of these brownies by switching out the vanilla flavor for another flavor of your choice. Same with the frosting. This is a very adaptable recipe perfect all year round.