Prepare an 8" square baking pan by lining with parchment paper. To make this step easy, crinkle your parchment paper into a tight ball, then unfold.
Preheat oven to 350 F.
In a small saucepan, stir chocolate and butter or coconut oil over low heat just until melted and smooth. Set aside to cool.
In a large mixing bowl, combine eggs, sugar, and brown sugar or coconut sugar. Mix on medium-high 4-5 minutes until light and smooth. Mixture should be about double in size.
Mix in salt, vanilla, and chocolate mixture, scraping sides with a spatula as needed, until smooth and combined.
Add cocoa powder and mix until smooth.
Spread brownie batter into prepared pan.
Bake for 20-25 minutes until toothpick inserted comes out with fudgy crumbs. Be careful to not over-bake.
When brownies are done, gently press toppings onto the top to create a fun Halloween scene.
Allow brownies to cool before serving.