Preheat your oven to 350°F (175°C). This ensures your brownies bake evenly and come out perfectly.
Line a 9x13 inch baking pan with parchment paper, allowing some overhang for easy removal later.
In a medium saucepan over low heat, combine the butter and chopped unsweetened chocolate. Stir continuously until fully melted and smooth. Remove from heat and let it cool slightly.
Add the granulated sugar to the melted chocolate mixture and stir until well combined. Next, add the well-beaten eggs and mix until fully incorporated.
In a separate bowl, whisk together the all-purpose flour. Gradually add this to the chocolate mixture, stirring until just combined.
Fold in the bittersweet chocolate chips and toffee chips, ensuring they are evenly distributed throughout the batter.
Gently fold in the broken-up pretzels to give your brownies that delightful crunch.
Pour the brownie batter into the prepared baking pan and spread it evenly. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for about 10 minutes before lifting them out using the parchment paper. Let them cool completely on a wire rack before slicing into squares.
