Astrobaking: Heart Nebula Cheesecake

Our regular astrobaker Katharine Kilgour turns to one of the most familiar deep-sky objects as inspiration for this Valentine's Day cheesecake.

Katharine Kilgour likes to combine her love of astronomy with her love of cooking, making tasty treats to feed herself, her friends and her family Astro-boy (aged 12), Astro-girl (aged 16) and Astro-dad.

Image credit: Katharine Kilgour


February! Nights are dark, but it’s freezing in the back garden and two pairs of gloves impede the operation of the telescope. However, the sky is obliging the season with the heart nebula situated high above us, visible all night, in Cassiopeia for Valentine’s day. Perhaps ‘visible’ is an exaggeration because, although we can try to convince ourselves we have seen the ‘smudge’ through our telescope, the equipment we have is never going to allow us to pick out the heart-shaped gas clouds from the surrounding Milky way!

Astro Dad to the rescue presenting me with a heart nebula valentine’s card, courtesy of a Hubble telescope image and a printer! So I’ll reciprocate with a heart nebula dessert.

Don’t let the words ‘water bath’ put you off, it’s just a technical way to say ‘roasting tin with hot water in it’. You also need to wrap the outside of your tin with two layers of tin foil. we are looking to reduce the intensity of the oven heat as well as prevent water seeping into the base. Astro boy says it is like cooking under the reflection of the Moon rather than in the Sun’s full glare, if an astronomical analogy for the cooking method helps!


For the base:

200g digestive biscuits

50g block butter, melted


For the topping:

600g cream cheese

150g caster sugar

3 egg yolks

3 whole eggs

1 tablespoon vanilla essence

2 tablespoons lemon juice

100g dark chocolate, melted and cooled

300g raspberries, fresh or frozen 

Baking glitter

23cm spring-form tin and a roasting tin it can sit in



1. Wrap the outside of a springform baking tin in two layers of tin foil.


2. Crush the biscuits. This is easiest in a food processor, although you can also put them in a freezer bag and use a rolling pin. Add the melted butter and mix thoroughly.


3. Press into the base of the wrapped tin and pack it firmly. A potato masher can help! Refrigerate to set.


4. Heat the raspberries in a pan with a tablespoon of water. Once soft, press through a sieve to remove the pips. You will have a bowl of juice and only a spoonful of pips left.


5. Pour half the juice into a clean saucepan and simmer gently until you have a thick red paste. Allow to cool. Into the other half of the raspberry juice, mix 50g icing sugar and set aside for serving. Heat the oven to 180°C. And boil the kettle!


6. Beat together the cream cheese and sugar until smooth. Add the egg yolks one at a time, mixing each one as you go until they are thoroughly mixed. Stir in the vanilla and lemon juice.


7. Put two table spoons of the creamy coloured mixture into a piping bag. Take a quarter of the remaining mixture and stir in the thickened raspberry puree.  Place this in another piping bag. Stir the melted chocolate into the remaining mixture and spread over the biscuit base.


8. Now it’s time to get arty! Copy a picture of the Heart Nebula. Pipe the red mixture into the chocolate base in a heart shape then use the pale mixture to swirl in the nebula gas clouds and dot the stars into place.


9. Now to use the water bath. Carefully place the cheesecake tin into your roasting tin, slide onto the middle shelf of your oven and pour 3cm depth of water from your kettle into the roasting tin


10. Bake for approximately 45 minutes. When cooked it will be set but still wobbly in the middle. Remove from the roasting tin and run a knife round the edge of the tin. This will help to prevent the cheesecake cracking while it cools.


11. Once cool refrigerate for two hours or until ready to serve. Add some edible glitter to give the nebula its sparkle and serve with the sweetened raspberry juice sauce.


12.  If you prefer a different flavour you can bake in a different ‘light spectrum’. I made ginger and orange, using ginger biscuits for the base. Leave out the chocolate and add orange zest and food colouring to the mixture for the heart.

All images copyright Katharine Kilgour


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