Pre-heat your oven to 370℉/180℃. Line an 8" Square Pan with greaseproof paper.
In a small bowl, break up the dark/semi-sweet chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn. Alternatively, set up a double boiler. Do this by placing a heatproof bowl over a small pot of simmering water. Add the chocolate to the heatproof bowl and stir until melted.
In a large mixing bowl, whisk together melted butter and both sugars. With an electric/stand mixer, mix for a good 3-5minutes so it is totally combined. Add the eggs and whisk again.
Add the melted chocolate slowly and combine once again.
Add the flour and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Add in the crushed mini pretzels and stir to combine.
Pour into the lined pan and drizzle over the caramel sauce.
Bake 25 minutes until the top is shiny and it's still just a little wobbly in the middle. Let cool before topping with more caramel and pretzels, then serve!