Preheat oven to 190ºC. Add bacon and brown sugar to a large bowl and toss until bacon is coated.
Top a baking sheet with a wire rack and lay bacon on the rack. Put the baking sheet on the top rack of the oven and bake until crisp, about 15 mins. Remove from the oven, cool, then chop ½ into small pieces and half into larger chunks.
Preheat the oven to 180ºC. Oil the sides and bottom of a 9×13-inch baking pan. Line the baking paper on pan.
Whisk the flour, salt, and cocoa powder together.
Microwave chocolate and butter in a large glass bowl for 30 secs increments, stirring each time until the chocolate and butter are melted and smooth.
Add the sugars and vanilla to the chocolate and whisk until completely combined.
Add 3 eggs to the chocolate mixture and whisk until combined, then add the remaining eggs and whisk until combined.
Sprinkle the flour mixture, half the pecans and the small pieces of bacon over the chocolate mixture and fold in using a rubber spatula until just a bit of the flour mixture is visible.
Pour batter into the prepared pan and smooth out into an even layer. Top with remaining pecans and the larger chunks of bacon.
Bake in the center of the oven for 30 mins, rotating the pan halfway through the baking time, until a toothpick inserted into the center of the brownies comes out with a few moist crumbs sticking to it.
Allow brownies to cool, then lift them out of the pan using the parchment paper. Cut into squares and drizzle with caramel to serve.
Store at room temperature in an airtight container or wrap with plastic wrap for up to 3 days.