Bruno Loubet's tarte au sucre 5g (⅛oz) fast-action dried yeast 1 tbsp caster sugar 350g (12 oz) plain flour, plus extra for dusting 2 eggs, plus 1 egg yolk 160g (5¾oz) butter, softened and cut into cubes For the topping: 70g (2¾oz) crème fraîche 60g (2oz) caster sugar 60g (2oz) demerara sugar grated zest of 1 lemon In a mixing-bowl, dissolve the yeast in 175ml (6fl oz) lukewarm water, then add the sugar and 50g (1¾oz) of the flour. Whisk well, then cover with clingfilm and place in a warm place for about 15 minutes - the mixture should become bubbly and double in volume. Place the remaining flour in the bowl of an electric mixer fitted with a dough hook. Add the eggs, egg yolk, a pinch of salt and the yeast and mix on a medium speed. It will take about five minutes for the dough to gain some elasticity; then add the butter, a few cubes at a time, ensuring each is incorporated before adding the next. Mix for a further two minutes, until the dough is elastic. Place the dough in a lightly floured bowl, cover with a damp cloth and refrigerate for an hour. Form the dough into a ball, place on a lightly floured non-stick baking-sheet, and roll out to a circle of 32-35cm (12½-13¾in) diameter. With the tip of a finger, push the dough about 1cm (½in) in from the edge all around to form a small rim. Spread the crème fraîche all over the tart then sprinkle over the sugars and lemon zest and bake for about 20 minutes, until it feels spongy and is golden brown all over. Check that the underneath is cooked, too. Serve with a good jam.