Preheat oven to 175°C / 350°F. Line a small baking tin with parchment paper and set aside.

In a bowl, whisk together the flour, cocoa powder and baking powder; break up any lumps and set the dry mix aside.

Cut the salted butter into chunks and place in a heatproof bowl with the semisweet/dark chocolate chips.

Set the bowl over a saucepan of simmering water (bain-marie), making sure the bottom of the bowl does not touch the water. Stir occasionally until the butter and chocolate are fully melted and smooth, then remove the bowl from the heat.

Add the granulated sugar to the melted chocolate in two roughly equal additions, stirring well after each addition until the sugar is incorporated and the mixture is glossy.

Crack the eggs into the chocolate mixture one at a time, stirring well after each egg until the mixture is smooth and uniform.

Pour the chocolate mixture into the bowl with the dry ingredients. Fold gently with a spatula until just combined — do not overmix.

Pour the batter into the prepared tin and smooth the top with the spatula.

In a separate small bowl, combine the panko breadcrumbs, olive oil and flaky sea salt; toss until the panko is evenly coated.

Evenly spread the panko mixture over the top of the brownie batter.

Bake for 25 minutes. Remove from the oven, loosely tent with foil (do not press the foil onto the panko), and return to the oven to bake for a further 20 minutes. The panko should be golden and a toothpick inserted near the center should come out with a few moist crumbs (not wet batter).

Remove the pan from the oven and allow the brownies to cool completely in the pan. Once cool, lift out on the parchment and cut into bite-sized pieces.