Preheat oven to 350℉ (180℃)
Lightly grease a 9"x13" cake pan by spraying with baking spray or greasing with butter.
Place eggs and vegetable oil in a bowl. Whisk until well combined. Set aside for later.
¾ Cup Vegetable or Canola Oil, 4 Large Eggs
In a large bowl combine flour, cocoa powder, sugar, cornstarch, baking powder and baking soda. You can use an electric mixer or just stir it by hand—either works!
¾ cup Cocoa Powder, 2 cups All Purpose Flour, 2 Tablespoons Corn Starch, 2 teaspoons Baking Powder, ½ teaspoon Baking Soda, 2 cups Granulated Sugar
Add oil and eggs to the mixing bowl. Mix until well combined.
Slowly pour brewed coffee into bowl while continuing to mix, scraping the bowl occasionally. The batter should be smooth.
1 ¼ Cup Brewed Coffee, may substitute water
Pour the cake batter into greased baking pan.
Bake for 40 - 45 minutes. Cake will be well risen and a toothpick inserted in the center of the cake will come out clean.
Place cake on a cooling rack for 10 minutes. Make peanut butter sauce during this time.
Place peanut butter, sweetened condensed milk and whole milk in a mixing bowl. Whisk well until combined. Tip: If the peanut butter isn’t blending well, microwave the mixture for 20 seconds, then whisk again.
1 Cup Creamy peanut butter, 1 Can Sweetened condensed milk, ½ Cup Whole Milk
After the cake has cooled for 10 minutes, use the handle of a wooden spoon or a large straw to poke holes all over it. Tip: As soon as you poke the holes, start pouring the peanut butter sauce over the cake so it soaks in better.
Slowly pour the peanut butter sauce over the warm cake, allowing it to seep into the holes. Jiggle the pan or tap lightly on a countertop to ensure sauce seeps into the holes.
Let cake cool completely (approximately 30 minutes) then wrap in plastic and place in fridge for 1 hour.