Preheat your oven to an appropriate temperature for baking.

In a medium saucepan over low heat, melt the butter and chocolate together until smooth and glossy.

Remove from heat and whisk in brown sugar until fully combined.

Add the lightly whisked eggs to the chocolate mixture, stirring until combined.

Stir in vanilla extract, then add flour, cocoa powder, and salt. Mix until just combined.

Prepare a baking pan by lining it with parchment paper, then pour the brownie batter into the prepared pan.

Bake until set but slightly soft in the center, about 25-30 minutes.

Meanwhile, prepare the caramel layer by combining sweetened condensed milk, golden syrup or maple syrup, and butter in a clean saucepan over low heat until melted and smooth.

Once the brownies are done baking, remove them from the oven and pour the caramel mixture over the brownie layer.

Return the brownies to the oven for an additional bake until the caramel is slightly bubbly around the edges.

Let the brownies cool completely in the pan before lifting them out using the parchment paper overhang.

Cut into squares and serve.