Preheat the oven to 160C fan / 180C and prepare a 23cm springform deep cake tin with non-stick parchment paper (ensure there are no gaps so no chance of mixture leaking!).
In a medium bowl mix together the milk and lemon juice and leave to sit for 10 minutes or so until it starts to thicken / you see lumps!
Add the eggs, melted butter and vanilla extract to the bowl and mix to combine.
In a large bowl, sift together the dry ingredients - gluten free plain flour, cocoa powder, caster sugar, light brown sugar, gluten free baking powder, bicarb and xanthan gum.
Add the wet mix into the dry ingredients and mix together until well combined, there should be no pockets of dry ingredients visible. I do this on a slow speed with an electric hand mixer, trying not to overmix.
Stir in the coffee (coffee mixed with boiling water), it will make the cake batter much looser but nice and glossy. Pour this into your cake tin and bake in the preheated oven for around 45 minutes until fully baked. Check that it's cooked by sticking a skewer into the centre of the cake - if it comes out clean, then it’s done.
Leave to completely cool in the tin - don’t take it out as extra layers need to be added still.
For the ganache, place the chopped chocolate in a glass heat proof bowl and put to one side. Heat the double cream in a saucepan on a low heat until it's just starting to simmer, then remove from the heat and pour over the chocolate. Leave for a few minutes then stir together, the chocolate will have melted and you are left with a lovely thick glossy pourable ganache.
Pour it over the cooled cake and allow it to spread to the edges.
For the cornflake layer, either melt the chocolate in a bain marie or in the microwave in short bursts and then stir through the cornflakes to fully coat them. Then stir through the crushed mini eggs. Spoon the mixture on top of the ganache in a level layer.
Now at this point you have a choice:If you want to just tuck in straight away, feel free to remove the tin and tuck in - the top would be a little messier this way but it’s delicious warm like this.If you want to wait, place in the fridge for a couple of hours, the ganache and top will firm up and you can then cut clean slices. Do leave to come up to room temperature so the cake is squidgy again!The best of both worlds is placing it in the fridge to firm up so you can cut clean slices and then warm up portions in the microwave. The ganache layer will become more saucey and the fudge cake is always delicious warm.You can top with extra mini eggs to serve too!