Preheat your oven to 160℃, line an 8-inch square cake pan with parchment and grease lightly with baking spray or butter.

Gently heat butter, cocoa, salt and sugar in a bowl set over a pan of simmering water (double boiler) until the butter has melted and combines with the cocoa, salt and sugar to form a glossy mixture.

Set the mixture aside to cool.

Meanwhile, mix the peanut butter, egg, sugar, salt and vanilla in another bowl. You’ll have a thick, sticky doughy mixture.

When it is barely warm, beat in the eggs, one at a time, followed by the vanilla till they are well incorporated.

Now add the flour and Alice recommends 40 vigorous strokes to get a shiny, lump-free, smooth batter.

Pour it into the prepared pan and spread evenly. Pinch little nuggets of the peanut butter dough and gently push into the brownie batter.

Bake for 25-30 minutes and turn off the oven while a few crumbs still cling to a skewer inserted into the brownie (very important to get a gooey texture).

Remove from the oven and let it sit in the pan for 10 minutes.

Gently ease out the brownies, and cool on a wire rack before cutting and storing in an airtight tin.