In a large bowl, combine melted butter, granulated sugar and light brown sugar. Mix with a hand or stand mixer for 1 minute.
Add the eggs, cocoa powder, vanilla extract and salt. Mix until well combined, then scrape down the bowl.
Add in the flour and mix until combined. Scrape down the bowl.
To assemble the brownie pie, spread half of the brownie batter over the pie crust.
*Set a few tablespoons of caramel aside for drizzling later* Pour the caramel over the brownie batter (pour the caramel evenly throughout the whole pie in order to avoid needing to spread it out as much as possible).
Evenly spoon the remaining brownie batter over the caramel layer (again spooning as evenly as possible to avoid needing to spread the batter as much as possible).
Use a silicone spatula or the back of a spoon to spread the brownie batter and cover the caramel layer. It's OK if the two layers mix a bit.
Bake for 50-60 minutes or until a toothpick comes out clean.
Once it has cooled, drizzle remaining caramel over the top and sprinkle with salt (if desired).