Crumble and Custard cupcake

Here are the ingredients to make this delicious recipe!
Recipe –
For the Rhubarb Goo…
300g of washed ‘field grown’ or ‘forced’ rhubarb
3 tbsp caster sugar
zest of an orange (optional)
vanilla pod/vanilla extract (optional)

For the syrup…
The juice from the roasted rhubarb, cooked down and reduced by half

For the Sponge…
125g self raising flour
125g caster sugar
125g soft unsalted butter
1/4 tsp bicarbonate of soda
2 lg eggs
1.5 tbsp milk
1/4 tsp vanilla extract
a few spoons of the rhubarb goo

For the crumble topping…
80g plain flour
20g porridge oats
1 tsp caster sugar
1 tsp demerara sugar
pinch salt
40g melted unsalted butter