Make the shortbread crust

• Cream together the softened butter and sugar.
• Mix in the flour and salt until combined.
• Press into a lined 9x9 pan and make dots with a fork.

Bake the shortbread

• Bake at 350 °F until lightly golden.

Prepare the brownie batter

• In a bowl, cream the melted butter and sugar, then microwave gradually until the sugar dissolves and the mixture is shiny. Set aside.
• In another bowl, mix together the eggs, cocoa powder, salt, baking powder and vanilla.
• Combine the egg mixture with the butter mixture, then mix in the flour.

Bake the brownie layer

• Spread the brownie batter over the baked shortbread.
• Bake at 350 °F until the middle is just barely set.
• Let cool to room temperature.

Make the salted caramel

• Cook the butter and brown sugar in a saucepan over medium heat until dissolved.
• Add the condensed milk and heavy cream and continue cooking until thicker and a bit darker.
• Stir in the vanilla and salt, then pour over the cooled brownies.

Chill the caramel layer

• Set the brownies in the fridge until the caramel firms up.

Add the chocolate top

• Melt the semi-sweet chocolate and pour it over the caramel.
• Sprinkle with flaky salt and set in the fridge until fully set.