Start by making the brown butter. Place the butter in a saucepan over a medium heat and melt, then leave it on the heat to gently bubble until the milk solids turn deep golden brown and it smells nutty. Pour into a bowl, then set aside to cool completely.

Place the cooled brown butter and both sugars in a mixing bowl. Beat together until pale, light and fluffy; if you have a stand mixer, this will take 4–5 minutes. Add the vanilla and egg, then beat again.

In a large bowl, whisk together the flour, baking powder and salt. Add to the butter and egg mixture and fold through until combined. Add most of the chopped white chocolate and pretzel pieces, reserving some of each for the tops of the cookies, and fold them through. Transfer the dough to the refrigerator to chill for 15 minutes.

Line two large baking sheets with baking paper. Take large scoops (about 2 tablespoonfuls) of dough, roll them in your hands, then space them out across the sheets.

Press a few pieces of white chocolate and pretzel onto the tops of each ball, then place the sheets back in the refrigerator to chill for 15 minutes. Preheat the oven to 180°C/160°C fan/350°F/Gas 4.

Bake the cookies for 10–12 minutes, until set and lightly golden at the edges but still gooey and soft in the middle

Remove from the oven. Leave to cool on the baking sheets for 10 minutes before transferring to a wire rack to cool completely. Sprinkle with flaky sea salt.