Campfire Cupcakes

I have simply given up on trying to make cakes look good with some elaborate decoration. I simply cannot do it. Therefore, I set out to bake cakes that look good without excessive and lurid, bake-off style decoration; things like an upside-down fruit cake, they are capable of looking beautiful on their own terms. However, today I fancied cupcakes, and that particular paradigm doesn't work, they need some sort of decoration, icing. And this is where my rules set in (I'm a bit of a purist unfortunately, you see): I cannot abide food colouring, the icing must be pure white or nothing (but you will see I contradict myself on this later), the most embellishments on top of the cupcake must be a maximum of a sugar flower or edible ball bearings. Lastly, simple flavours make the best cupcake. You're at home, not in a bakery. Get over yourself.
Onto my contradiction, I iced these basic lemon and vanilla cupcakes with a fabulous glossy marshmallow, and fancied toasting them under the grill. And I burned them, call it stumbling at the last hurdle. As a result, I decided to call them campfire cupcakes, because marshmallows are supposed to be burned, right? RIGHT?!
1)Preheat the oven to 170 degrees, and line a muffin tin with paper cases.
2)Sometimes I use stork, and more often unsalted butter that's been softened, either way, cream 150g of it with 150g caster sugar until light and fluffy. Add the zest of one lemon, and beat in one egg and a third of 150g plain flour with one teaspoon of baking powder and half of bicarbonate of soda, then add another egg, another third, then the final egg, the rest of the dry ingredients and the juice of the lemon, and a teaspoon of good vanilla extract, or paste. Once everything is completely combined, add 2 tbsp milk to get the batter to a nice dropping consistency, but remember (unlike I did) to take the milk out of the fridge before you start, or the batter will just curdle.
2)Use an ice cream scoop to dollop equal spoonfuls of batter into the tin, and bake for 10-15 minutes until spongy and golden brown. Yes, a cliché though it now is, a skewer inserted in the biggest cupcake will come out clean.
3)While the cakes are baking, separate 4 eggs, so you get the whites in a large bowl. I used to do this by flipping the yolk between its halved self, but I always broke the yolk then, and when some gets in the whites the whole concoction is contaminated and you have to start over. You're not supposed to, but I just crack the egg in my hand and let the whites fall out between my fingers. Add 1 cup of granulated sugar, a pinch of fine salt, and juice 1/2 lemon.
4)What you're making here is marshmallow, and although you usually use gelatin for this, egg whites were the original way of making marshmallows before confectioners decided to innovate for money. Set the bowl over a pan of gently simmering water, after the ingredients have been combined with a large whisk, and whisk more until the sugar dissolves and the mixture is hot to the touch. Then, transfer to an electric whisk and whisk for about 4 minutes, until the marshmallow is incredibly stiff and glossy.
5)Use a small palette knife to spread a generous dollop of marshmallow onto each cupcake, and spread it around, making peaks and swirls as you do so. Heat a grill, then place the cupcakes under it (so you may aswell keep the cupcakes in their tin) for just about 30 seconds, until brown (or a lovely shade of charcoal black for me).