Preheat the oven to 350°F. Lightly grease a 9" x 13" pan
Line pan with parchment paper, for easy removal.
Crack eggs into a bowl, add cocoa, salt, baking powder, and vanilla, and beat until smooth.
In a medium-sized saucepan set over low heat, melt butter, then add sugar and stir to combine. Continue to heat, just until mixture is hot (about 110°F), but not bubbling; it'll become shiny as you stir. Heating the mixture to this point will dissolve more of the sugar, which will yield a shiny top crust on your brownies.
Add hot butter/sugar mixture to the egg/cocoa mixture, stirring until smooth.
Add flour and chips, stirring until smooth.
Spoon batter into prepared pan.
Bake brownies for 30 minutes, until a cake tester inserted into the center comes out clean, or with a few moist crumbs clinging to it. Brownies should feel set on the edges, and the center should look moist, but not uncooked. Remove pan from oven and cool.
Top cooled brownies with warm caramel. For caramel layer, melt caramel squares with 1 Tablespoon heavy cream, stirring until smooth. Chill until caramel is set.
Top brownies with warm ganache. Sprinkle with chopped pecans. Chill until set.