Rub butter into flour and icing sugar until the mixture looks like breadcrumbs.
Mix in egg yolk and water to form a firm dough and chill for 30 minutes.
Preheat oven to 180°C fan and roll pastry into a circle 5cm larger than the tin.
Line the flan tin with pastry and chill in the fridge for 15 minutes.
Prick pastry base, line with parchment and beans, then bake blind for 10 minutes.
Remove beans and paper and bake for 7 more minutes until dried and pale golden.
Melt butter and chocolate together in a pan over low heat until smooth.
Remove from heat and stir in the sugar, flour, and eggs one at a time.
Pour mixture into the pastry case and bake at 180°C for 12 minutes until slightly wobbly.
Cool slightly and dust with icing sugar before serving with strawberries and cream.