Preheat oven to 350 and line 9?x13? pan with nonstick foil.
In a large bowl, add 4 eggs, and beat with cocoa, salt, baking powder, and vanilla. Stir until fully combined and smooth.
In the microwave, melt butter.
When melted, add sugar, and stir to combine.
Add warm butter/sugar mixture to the egg/cocoa mixture, stirring until smooth.
Add the flour to batter and stir until fully incorporated.
Spread batter into prepared pan, and smooth as needed.
Sprinkle on chopped Twix Bars.
Pour on caramel and swirl into the brownies a bit with a toothpick.
Bake brownies about 30 minutes.
Test for doneness by inserting a toothpick.
You should find moist crumbs.
Cool and cut into small bite sized squares.