Fudgy brownies are the epitome of a chocolate lover's dessert, with a rich cocoa flavour and gooey texture that makes you want more. As with most , there's no need for complex instructions, but many call for an expensive list of ingredients, including chocolate with a high-percentage cocoa content and often a blend of white, milk, and dark chocolate.

's recipe is unique in using Bourneville chocolate, a dark but sweet creation by Cadbury. The chocolate bar has 36% cocoa, so it's balanced with bitterness and sweetness, which Mary deems just right for her "ultimate" brownies. Sharing the delicious formula in her cookbook, Cook and Share, Mary branded the brownies her "favourite", stating they have "a wrinkled top and a gooey middle", which comes down to one simple step in the recipe.

Ingredients

360g Bournville plain chocolate (two 180g packets), broken into pieces

225g butter, cubed, plus extra for greasing

225g light muscovado sugar

Four eggs, beaten

75g self-raising flour

One tsp vanilla extract

75g chocolate chips

You will need a hot oven to ensure the brownies cook evenly and rise a little while they bake, so start by preheating the oven to 180C/160C Fan/Gas 4.

Next, grease and line a 30 x 23cm (12 x 9in) traybake tin with non-stick baking paper, wrapping it around the sides and base.

Place the broken-up chocolate and cubed butter in a large heatproof bowl to make the mixture. Transfer the bowl to rest on a pan of simmering water, ensuring the bottom does not touch the water directly.

Heat the mixture until melted, stirring to combine. Remove from the heat and add the sugar and eggs. Mix well until smooth. Stir in the sieved flour and vanilla, followed by the chocolate chips.

Pour the raw chocolate mixture into the prepared tin and bake for about 45 minutes, until well risen and set around the edges, with a slightly soft centre - this is essential for ensuring a perfectly fudgy texture.

Remove the brownies from the oven and cool in the tin before slicing into 24 even squares.