Preheat the oven to 350 degrees F and line an 8x8-inch baking pan with parchment paper and set aside.
In a medium bowl, whisk together the flour, cocoa powder, salt, and baking powder and set aside.
In a large microwave-safe bowl, melt the butter on 30-second intervals until melted. Whisk in the sugar, heavy cream, eggs, and vanilla until smooth.
Add the dry ingredients to the wet ingredients and mix just until combined. Pour the brownie batter into the prepared baking pan.
Unwrap the Twix bars and use 9 of them to press into the center of where each cut square will ideally be. Use a rubber spatula to spread the batter over the top of the bars. The batter covered bars will sit higher than the rest of the batter, this is fine as the batter will bake up around the candy bars and they will be level once baked.
Bake the brownies for 20 to 22 minutes, a toothpick should come clean from the center.
Remove from the oven and use the edges of the parchment paper to help you transfer the brownies to a cooling rack and allow to cool completely.
Drizzle the caramel sauce over the top of the brownies and chop up the remaining Twix bars and scatter them on top of the brownies. Slice and serve.