4Prepare an 8x8 baking dish by lining it with parchment paper.
5Prepare an 8x8 baking dish by lining it with parchment paper.
6Prepare an 8x8 baking dish by lining it with parchment paper.
7In a medium saucepan, melt the butter over medium heat.
8In a medium saucepan, melt the butter over medium heat.
9In a medium saucepan, melt the butter over medium heat.
10Once butter is melted, remove from heat.
11Once butter is melted, remove from heat.
12Once butter is melted, remove from heat.
13While butter is hot, add the oil, granulated sugar, and brown sugar, whisking vigorously to combine.
14While butter is hot, add the oil, granulated sugar, and brown sugar, whisking vigorously to combine.
15While butter is hot, add the oil, granulated sugar, and brown sugar, whisking vigorously to combine.
16Pour mixture into a large mixing bowl and let cool for 5-10 minutes.
17Pour mixture into a large mixing bowl and let cool for 5-10 minutes.
18Pour mixture into a large mixing bowl and let cool for 5-10 minutes.
19Once the mixture has cooled, add the vanilla, eggs, and egg yolk.
20Once the mixture has cooled, add the vanilla, eggs, and egg yolk.
21Once the mixture has cooled, add the vanilla, eggs, and egg yolk.
22Whisk vigorously again until the mixture is glossy and smooth.
23Whisk vigorously again until the mixture is glossy and smooth.
24Whisk vigorously again until the mixture is glossy and smooth.
25Add the cocoa powder and whisk to combine.
26Add the cocoa powder and whisk to combine.
27Add the cocoa powder and whisk to combine.
28Add the flour, baking powder, and salt, and fold together with a rubber spatula until combined.
29Add the flour, baking powder, and salt, and fold together with a rubber spatula until combined.
30Add the flour, baking powder, and salt, and fold together with a rubber spatula until combined.
31Pour batter into the prepared baking pan.
32Pour batter into the prepared baking pan.
33Pour batter into the prepared baking pan.
34Bake for 32-35 minutes or until the center is set and a toothpick inserted comes out clean.
35Bake for 32-35 minutes or until the center is set and a toothpick inserted comes out clean.
36Bake for 32-35 minutes or until the center is set and a toothpick inserted comes out clean.
37Let brownies cool for 30 minutes in the pan, then lift them out onto a cooling rack and let cool completely.
38Let brownies cool for 30 minutes in the pan, then lift them out onto a cooling rack and let cool completely.
39Let brownies cool for 30 minutes in the pan, then lift them out onto a cooling rack and let cool completely.
40Once brownies have cooled, make the buttercream by adding the softened butter to the bowl of a stand mixer fitted with the paddle attachment (or use an electric hand mixer).
41Once brownies have cooled, make the buttercream by adding the softened butter to the bowl of a stand mixer fitted with the paddle attachment (or use an electric hand mixer).
42Once brownies have cooled, make the buttercream by adding the softened butter to the bowl of a stand mixer fitted with the paddle attachment (or use an electric hand mixer).
43Cream the butter for about 2 minutes on medium-high speed until light and fluffy.
44Cream the butter for about 2 minutes on medium-high speed until light and fluffy.
45Cream the butter for about 2 minutes on medium-high speed until light and fluffy.
46Lower the speed and add the powdered sugar gradually.
47Lower the speed and add the powdered sugar gradually.
48Lower the speed and add the powdered sugar gradually.
49Once incorporated, increase speed to medium-high and beat for another 2 minutes, scraping down the sides as needed.
50Once incorporated, increase speed to medium-high and beat for another 2 minutes, scraping down the sides as needed.
51Once incorporated, increase speed to medium-high and beat for another 2 minutes, scraping down the sides as needed.
52Add the vanilla and heavy cream (starting with 1 tablespoon and adding more if needed), and beat again on high speed for 1 minute.
53Add the vanilla and heavy cream (starting with 1 tablespoon and adding more if needed), and beat again on high speed for 1 minute.
54Add the vanilla and heavy cream (starting with 1 tablespoon and adding more if needed), and beat again on high speed for 1 minute.
55Add the crushed Oreos and beat on high speed until incorporated.
56Add the crushed Oreos and beat on high speed until incorporated.
57Add the crushed Oreos and beat on high speed until incorporated.
58Frost the cooled brownies with a thick layer of buttercream, using an offset spatula to smooth out the top.
59Frost the cooled brownies with a thick layer of buttercream, using an offset spatula to smooth out the top.
60Frost the cooled brownies with a thick layer of buttercream, using an offset spatula to smooth out the top.
61Cut the brownies into 9 squares.
62Cut the brownies into 9 squares.
63Cut the brownies into 9 squares.
64Garnish the top of each brownie with a few pieces of crushed Oreo.
65Garnish the top of each brownie with a few pieces of crushed Oreo.
66Garnish the top of each brownie with a few pieces of crushed Oreo.