To make pastry, process flour, sugar and butter until mixture resembles breadcrumbs. Add egg yolk and the water, process until mixture just comes together. Shape into a disc, wrap in plastic wrap. Refrigerate 30 minutes.
Make frangipane. Process butter, nuts, sugar and flour until it forms a paste. Add eggs, process until combined.
Grease a 20cm x 30cm (8-inch x 12-inch) slice pan, line base and sides with baking paper. Roll pastry between sheets of baking paper until large enough to line pan. Ease pastry into pan, press into sides, trim edge. Refrigerate 20 minutes.
Preheat oven to 180°C (160°C fan forced). Line pastry with baking paper, fill with dried beans or rice. Bake 15 minutes. Remove paper and beans, bake 10 minutes or until pastry is golden and dry. Cool.
Spread frangipane over base.
Halve peaches, remove stones. Cut each half into three wedges. Arrange wedges on top of frangipane.
Bake tart 55 minutes or until browned and set (cover with foil if overbrowning). Stand tart 15 minutes before serving.