Chocolate and beet brownie bars recipe

For the purple batter: Preheat the oven to 190°C (170° fan) | 375F | gas 5. Pulse together the oats and ground almonds in a food processor until the oats are ground. Tip into a bowl and set aside until needed.

Rub the beetroot with the oil and arrange on a baking tray. Roast for about 1 hour until the flesh is very tender to the point of a knife. Remove from the oven and leave to cool for 15 minutes.

After cooling, peel and cube the flesh. Combine with the milk in a food processor and puree until smooth, scraping down the sides of the processor from time to time; add more milk as needed to achieve a smooth puree. Scrape into a large mixing bowl.

Reduce the oven to 180°C (160° fan) | 350F | gas 4. Grease and line a 23 cm | 9" x 32 cm | 13" baking tin with greaseproof paper.

Cream the butter with the vanilla extract and sugar in a mixing bowl until pale and fluffy, about 2-3 minutes. Beat in the eggs one by one, mixing well between additions.

Gently stir in the flour, salt, and baking powder, taking care to avoid over-mixing the batter.

Stir in the prepared beet puree and the prepared oat and almond mixture.

If desired, tint the batter by mixing in some purple food colouring, one drop at a time, until you have achieved the desired colour. Chill the batter until needed.

For the base layer: Melt the butter in a small saucepan set over a medium heat. Set aside to cool.

Pulse the biscuits in a food processor until they resemble breadcrumbs. Tip into a mixing bowl and stir in the sugar, salt, and enough melted butter so that the mixture resembles wet sand.1

Pack the mixture into the base of the prepared baking tin, smoothing its top with the back of a damp tablespoon. Bake for 10 minutes.

Remove from the oven and scrape the purple batter on top. Gently wrap the tin on a work surface to help settle the batter.1

Return the tin to the oven for about 35-40 minutes until the purple layer is set and dry to the touch on top; a cake tester should come out virtually clean from the centre. Remove to a wire rack to cool.

To garnish:

Once cool, turn out from the tin and cut into rectangular bars. Use a Y-shaped vegetable peeler or cheese slicer to shave some milk chocolate on top of the bars before serving