- Preheat your oven to 350°F (175°C). Greasing a 9x13 inch baking pan will help your brownies release easily. You can also line it with parchment paper for extra protection. 
- In a large mixing bowl, cream together the softened butter and sugar until it's light and fluffy. This should take about 3-4 minutes, and you'll notice a nice creamy texture forming. 
- Add the eggs one at a time, mixing well after each addition. The mixture should look smooth and glossy, which means you're on the right track! 
- Stir in the vanilla extract, making sure it’s evenly distributed. The aroma will be delightful and add a nice touch to your brownie batter. 
- In another bowl, whisk together the flour, cocoa powder, baking powder, and salt. Gradually add this dry mixture to the wet ingredients, stirring until just combined. Be careful not to overmix; a few lumps are okay. 
- Pour the brownie batter into the prepared pan and spread it evenly. Bake in the preheated oven for about 30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. 
- Let the brownies cool completely in the pan. Once cooled, spread the chocolate frosting on top for a rich finish. This is where the fun begins! 
- Sprinkle the crushed chocolate cookies over the frosting to create a 'dirt' effect. Then, place the gummy worms and candy tombstones on top for that spooky graveyard look. 
- Cut into squares and serve these delightful Halloween treats for kids at your next party. They'll be the star of the show!