Saffron, leek and mushroom tart

For pastry, place butter in the bowl of an electric mixer and using a paddle attachment beat on medium until pale and fluffy (5 minutes). Add egg and beat until combined. Reduce speed to low, add flour, 1 tsp fine cooking salt and 1 tsp cold water and beat until dough just comes together. Turn out onto a bench and knead until smooth. Form pastry into a disc, wrap and refrigerate to rest (1 hour).

Preheat oven to 200˚C. Bring pastry to room temperature (10 minutes). Roll out pastry on a lightly floured work surface to a rough 30cm x 40cm rectangle. Lightly grease a 3cm-deep 21cm x 32cm loose-based, fluted rectangular tart tin and line base and sides with pastry; trim excess pastry. Blind bake until dry to touch (15-20 minutes); cool in tin.

Meanwhile, for filling, reduce oven to 180˚C. Place leeks on a large tray lined with baking paper. Dissolve sugar in saffron mixture and vinegar in a small bowl. Whisk in olive oil and brush over leeks, reserving any remaining mixture. Bake until tender and just starting to brown (8-10 minutes); set aside.

Meanwhile, place cream, shallot, bay and peppercorns in 2 small saucepans; cook over low-medium heat, until mixture is infused. Strain mixture then return to pan; discard solids. Whisk in eggs, mustard and ½ tsp fine cooking salt until combined; cool slightly.

Place pastry tin on an oven tray and pour in egg mixture: top with leeks cut-side up. Bake until set and top is golden brown (30-35 minutes). Cool slightly in tin.

Heat a frying pan over high heat and add butter. When butter foams, add mushrooms and cook, tossing occassionally, until cooked (4-5 minutes).

Transfer tart to a platter, spoon over mushrooms, drizzle with any remaining saffron mixture and serve with mixed baby leaves on the side.