Preheat the oven to 350 degrees and prepare a 12x12 pan with parchment paper.
In a medium bowl, whisk together flour, cocoa powder and salt. Set aside.
In a stand mixer fitted with a paddle attachment, combine melted butter, oil and sugar on medium speed. Whisk until fully combined, about 1- 2 minutes.
Add eggs and vanilla extract. Mix until full combined, about 1 minute.
Fold in dry ingredients until just combined.
Place batter in prepared pan. Smooth into an even layer with a knife or offset spatula.
Bake for 25-38 minutes, or until a toothpick comes out clean. Place on a wire rack to cool.
Once brownies are cool, take them out of the pan and place in the fridge for one hour. (This makes it much easier to cut into shapes!)
Use cookie cutter to make hearts.