Follow these simple steps to create your Ghostly Caramel Marshmallow Brownies:

1. Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan and set it aside.
2. Melt the Butter: In a saucepan over low heat, melt the unsalted butter. Once melted, stir in the granulated sugar until combined.
3. Mix Wet Ingredients: Remove from heat and allow the mixture to cool slightly. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
4. Combine Dry Ingredients: In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt. Gradually add this to the wet mixture until just combined.
5. Pour Batter: Pour the brownie batter into the prepared baking pan, smoothing it out with a spatula.
6. Add Caramel and Marshmallow: Drizzle the caramel sauce over the brownie batter, then sprinkle the mini marshmallows on top.
7. Bake: Bake the brownies in the preheated oven for 25-30 minutes. The edges should look set, while the center might appear slightly underbaked; this is ideal for a fudgy texture. Allow to cool for about 15 minutes before slicing.