Rub 65g butter into flour and salt until it reaches a breadcrumb texture.
Mix vinegar with 150g water, add to dry ingredients to form a dough, and freeze for 10 minutes.
Flatten 250g butter between greaseproof paper into a square less than 1cm thick.
Roll dough into a rectangle twice the size of the butter, fold over butter, roll out, and fold again.
Refrigerate the pastry for 20 minutes.
Infuse lavender into caster sugar, then slice four apples into wedges and halve the rest.
Chill apple halves in the fridge on a rack and repeat pastry folding three times before refrigerating again.
Preheat your oven to 200°C.
Heat lavender sugar, 20g water, and lemon juice in a pan until a light caramel forms.
Remove from heat, add 50g butter and salt, and swirl to combine without stirring.
Arrange apples in the pan and heat on low for five minutes before cooling.
Roll out the final pastry to fit the pan and tuck the edges down the inside.
Bake for 30 minutes until golden and crisp.
Invert onto a plate immediately, cool for five minutes, and serve with clotted cream.