Preheat the oven to 350°F. Line your baking pan with parchment paper.
In a large bowl, whisk together brown sugar, granulated sugar and canola oil. Then add the eggs and vanilla bean paste. Whisk until well combined.
4 eggs, 1½ cups granulated sugar, ½ cup brown sugar, ½ cup canola oil, 1 tsp vanilla bean paste
In a saucepan over medium heat, add the dark chocolate chips and unsalted butter. With a spatula, stir frequently so the chocolate doesn't burn as it melts. Heat the contents and keep stirring until the butter and chocolate become a glossy sauce, about 2-3 minutes. Remove from the heat and dump in the cocoa powder. Mix together until combined and let the sauce cool for 2-3 minutes.
⅓ cup dark chocolate chips, 1 stick unsalted butter, ¼ cup unsweetened cocoa powder
Add the chocolate sauce straight to the batter. Whisk until smooth. Add in the coffee liqueur and whisk once more.
3 tbsp cold brew coffee or espresso liqueur
Pour in the flour, baking powder and salt. Switch to a spatula and gently fold the batter until the flour appears absorbed. Scrape the edges as you go.
1½ cups all purpose flour, 1 tsp baking powder, ¾ tsp salt
Pour the batter into the pan and smooth with your spatula. Place it in the oven at the center rack. Bake for 22 minutes or until the top of the brownies are just barely cracking and the edges appear set. A toothpick should come out clean when removed. Set aside to cool completely.
In the meantime, make the buttercream. In a stand mixer, beat the room temperature butter on medium high until whipped, 1-2 minutes.
1 stick unsalted butter
Add the powdered sugar and continue beating on medium until incorporated, about another minute. Then add the heavy cream slowly as you beat on medium high speed for 3 minutes, or until the buttercream has absorbed the cream and becomes white and fluffy. Let it rest for 5-10 minutes.
4 tbsp powdered sugar, 4 tbsp heavy whipping cream
Put the buttercream in a piping bag. When the brownies are completely cool, begin piping different sized ghosts all over the brownies. They can be all pointing different directions. Start with the outline and fill each one in with buttercream.
Use the chocolate chips for ghost mouths and the mini M&M's for eyes. Slice and serve!
mini M&M's, 5 large chocolate chips