Chocolate Toffee Oaty Squares

This recipe, which featured in Sainsbury's 'The Magazine' in August 1996 is so decadent that I only make it once in a blue moon. One good thing about 20 year old recipes is that they don't come with a nutritional analysis to scare you off completely, but you don't have to be a genius to realise that a traybake containing 200g plain chocolate, 240g Mars bars, 150g butter, 150g sugar and 150ml of double cream is going to contain a lot of calories per piece - and that most of the calories are from fat and sugar.

One thing had to be checked before starting the recipe; my husband has been complaining for ages that one of his favourite chocolate bars - Mars bars - seems smaller these days. He was right! In the 1990s a standard Mars bar weighed around 65g; today the bars in a multi-pack weigh a tad less than 40g. So the 4 bars in the recipe had to be replaced by 6 of today's bars.

The only change I made to the original recipe was to use plain chocolate as the first layer of the filling, rather than milk chocolate. It reduces the sweetness a bit, and increases the contrast between the chocolate and the 'toffee' layers. I cut the squares into a variety of sizes - some large pieces for my son to take home, and smaller pieces for us to eat - but I reckon you should get a minimum of 24 pieces out of the tray, although the recipe recommends 32.

Unless you don't like chocolate, you couldn't fail to enjoy these bars. The oat mixture makes a crisp base, the chocolate layer sets hard and the fudgy toffee layer, which is made from melted Mars bars and cream whisked together, stays melt-in-the-mouth soft - almost like a sauce on top, although it just holds it's shape.

Ingredients
225g plain flour
110g porridge oats
150g light brown sugar
1/2 teaspoon bicarbonate of soda
1/4 teaspoon salt
1 medium egg, beaten (I used the smallest from a box of large eggs)
225g deluxe milk chocolate, roughly chopped (I used 70% plain)
150ml double cream
Enough large Mars bars to give close to 240g (don't use mini bars or snack-sized as the proportion of chocolate to filling will be wrong)

Method
The recipe is made in a 9" x 13" (23 x 32cm) shallow tin. The nearest I could get to this, using an adjustable tin, was 10 x 12", which is a tiny bit larger. I lined the tin with baking parchment.

The dough can be made in a food processor, but I made it by hand, by rubbing the butter into the flour, oats, sugar, bicarbonate of soda and salt, then mixing in the egg until the dough held together when squeezed. If using a processor, pulse to cut in the butter, then again to blend in the egg. 3/4 of the dough was spread evenly into the baking tin, and pressed down firmly with the back of a metal spoon.

The 225g of chocolate was melted in a bowl over simmering water, then spread over the base, leaving a 1cm margin all round. The tray was then chilled until the chocolate was set - about 30 minutes in the fridge, or 10 minutes in the freezer.

Pre-heat the oven to 180C. Bring the double cream to the boil in a small heavy-based pan, then reduce the heat to a minimum and add the chopped Mars bars. Stir until the Mars bars have melted, then whisk until creamy. Pour this over the chocolate layer and spread evenly, leaving a small margin all round the edges, as before.

Crumble the remaining dough mixture over the top, as evenly as possible - there won't be enough to completely cover the surface.

Place the baking tin on a  baking sheet and bake for 25 minutes, then cool in the tin until the toffee has set - at least 2 hours. Cut into small squares.

I decided to push the boat out with these Chocolate Toffee Oaty Squares after Choclette, at Tin and Thyme, chose oats as the additional ingredient for this month's We Should Cocoa link-up. Each month either Choclette or a guest host chooses an ingredient, which must be used with some form of chocolate, to produce a tasty treat. I thought about making one of my chocolate flapjack recipes, but decided that a We Should Cocoa entry needed something a bit more out of the ordinary