In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder and salt until they're well combined.

In a separate large bowl, whisk together the oil, eggs, coffee and milk, until they're well combined. 

Sift the dry ingredients over the wet ingredients and then whisk together until the batter is completely smooth. 

Flip the cake over onto a tea towel and allow it to cool to room temperature.

If the butter is cold, cut it into cubes and place it into a light colored, medium size saucepan, over medium-low heat. 

Use a wooden spoon or rubber spatula to stir the butter occasionally. It will begin to bubble, continue stirring intermittently. 

Once it begins to foam, you won't be able to see what's happening so stir continuously, making sure to scrape the solids off the bottom of the pan. The milk solids will begin to settle on the bottom of the pan and darken in color.

Remove from the heat and continue stirring for another minute or so, until the butter darkens into an amber color.

Pour the butter, with all the little solid bits, into a heat safe jar and allow it to cool. Feel free to refrigerate it but stir often so it cool evenly. Bring it back to solid/soft room temperature.

Place the sugar and water in a medium saucepan and swirl the pan until the sugar is fully immersed in water. Place the saucepan over medium heat until the sugar dissolves and comes to a gentle simmer. Lower the heat to low and place the lid on the pan and allow the mixture to simmer for a couple minutes. 

Meanwhile, place the eggs in the bowl of a stand mixer, fitted with the whisk attachment, and turn the mixer up to high speed. Let it whip while the sugar is done cooking.

Use a candy thermometer to see when the sugar reaches 240F (116C), then lower the mixer to medium speed and slowly drizzle the hot sugar syrup into the thick and foamy eggs, while they are whipping. Create a stream going down the bowl, avoid hitting the whisk so it doesn't splatter the sugar syrup.

Turn the mixer back up to high speed and let it whip for 5-10 minutes, until the egg mixture is very pale and fluffy and is no longer warm.

Turn the mixer back down to medium speed and add in the butter and browned butter, 2 Tbsp of butter at a time, mixing until each chunk is fully combined and the buttercream looks smooth and creamy.

Scrape the sides and bottom of the bowl, add in the vanilla and peanut butter and turn the mixer up to high speed for 1-2 minutes. Smooth it out with a rubber spatula.

Spread a generous layer of peanut butter buttercream onto the first layer of cake. Microwave the extra peanut butter for 10 seconds and drizzle some on top of the buttercream.

Place the second layer on top and then repeat with the last layer.

Refrigerate the cake for at least an hour so it’s solid before frosting the outside with the rest of the buttercream.

To decorate like mine, smooth out the sides but use a small offset spatula to create the swirls on top. Dap some peanut butter randomly and swipe into the swirls. Top with crushed peanuts.