I made the compote and baked the cupcakes on day one, then made the frosting and assembled the cupcakes on day two. I found this easier since there is some chilling time involved so spacing out the steps helped.
To make the compote, combine the strawberries, sugar and 1 tablespoon water in a saucepan on low heat. Stir constantly until the fruit has softened and the liquid begins to look foamy, about 3 to 4 minutes. Combine the cornflour and 1 teaspoon water in a small bowl, and add it to the saucepan. Continue stirring for another 2 to 3 minutes, letting the compote simmer and thicken. The liquid will coat the back of a spoon as it thickens. Turn off the heat and let the compote thicken further and cool at room temperature, then refrigerate for 2 to 3 hours, or even overnight. It will thicken to a jam-like consistency which is easy to stir into the frosting.
To make the cupcakes, first preheat the oven to 175 C and line 9 muffin moulds with cupcake liners.
Melt the chocolate till smooth in a double boiler or microwave (in 10 second increments, stirring in between each). Set aside to cool.
In a large mixing bowl, beat the butter and sugar till pale and fluffy with a hand mixer on medium speed. Next, beat in the egg and vanilla. Add the melted chocolate, and stir by hand till combined but do not over-mix.
Sift in the flour, cocoa, baking soda and salt (if using). Fold it all in very gently till only a few streaks of flour remain. Now add the hot water, a little at a time, to prevent any lumps forming, and continue to fold the batter with a silicone spatula. I prefer doing this step by hand as a mixer could cause the hot water to splash here and there and make a mess.
If you still see lumps (I often do, despite my best efforts), beat with the hand mixer on low speed for a few seconds until smooth. The batter is slightly runny.
Divide the batter equally among the muffin moulds, filling them just about 3/4th of the way, and bake for 25 to 30 minutes until they have risen, developed slightly crackly tops and a toothpick poked in the center comes out clean.
Allow the cupcakes to cool in the tray for 10 minutes and then place them on a wire rack to cool completely, without peeling the liners off. They will fall slightly as they cool and have fairly flat tops.
To make the frosting, beat the butter and cream cheese with a hand mixer on low to medium speed, until smooth and creamy. Add the vanilla, sift in the icing sugar and beat until combined. Now add 1/4 cup of the chilled compote and stir it in, adding a couple more tablespoons if you want a deeper colour and/or flavour. You will have about 1/2 cup compote in all, but adding the whole amount will make the frosting too runny and could cause it to split. Plus, it's super berry flavoured with just 1/4 cup. Store any leftover compote in the fridge and spread it on toast!
Place the frosting in the fridge for at least 1 hour to be able to spread it onto the cupcakes, and about 4 hours if you want to pipe it. My recommendation is to avoid piping this as the combination of cream cheese and berry juices makes the frosting quite soft.
When chilled, spread it generously onto the cupcakes, decorate with strawberry pieces or small, whole strawberries and dig in! Store in the fridge at all times, they will keep for 3 to 4 days. Happy baking!