Preheat the oven to 170°C (150°C Fan, Gas Mark 3). Grease and line a 20cm x 30cm baking tray.

Break the Extra Dark Chocolate into pieces and place in a heatproof bowl, add the butter. Place in the microwave and heat for 1 minute and stir, continue to heat in 10 seconds bursts, stirring in between bursts until the mixture has melted, leave to cool for 5 minutes.

Stir the sugar into the melted chocolate mixture and whisk in the eggs and Vanilla Extract until you have a thick and glossy mixture. Sift the Cocoa Powder and Baking Powder on top and add the ground almonds. Gently fold the mixture together and finally add the Chocolate Chunks and stir into the mixture.

Pour the mixture into the prepared baking tray and smooth the top. Bake in the oven for 30 minutes until risen and crusty on top, the middle of the brownie will be slightly soft it will firm up as it cools. Leave the brownie to cool completely in the tin before removing. 

Divide the buttercream into 5 bowls; you will need to decrease the amount of buttercream in each bowl. Add Red Colour Gel to the bowl with the most buttercream in; add few more drops colour gel until you have a bright shade of red. Repeat the step adding Orange Colour Gel to the next fullest bowl, then yellow, green, blue and finally purple. Cover your bowls of buttercream in cling film to stop them drying out. 

Cut your tray of brownie into heart shapes using a heart shaped cutter about 10 cm in height – if you do not have a heart cutter you can cut them free hand using a stencil made of grease proof paper. 

Place your red buttercream into a piping bag fitted with a small star nozzle – if you do not have a star nozzle cut the end of your piping bag to create a ½ cm hole, you can pipe buttercream blobs onto your brownies. 

Pipe a red boarder around the edge of each brownie heart. Then repeat with the orange buttercream, piping inside the red boarder. Then repeat with the yellow, green and blue. Finish with the purple buttercream in the centre of the heart. 

Your brownie rainbow hearts are now ready to serve and enjoy. They can be stored in an airtight container for up to 3 days.