1.Cut four 25cm (10-inch) squares of muslin then cut out a hole from the centre of each square. Line four 10cm (4-inch) bundt pans (1-cup capacity) each with a muslin square.
2.Beat butter and sugar in a small bowl with an electric mixer until light and fluffy. Add ricotta, beat until combined, fold in crème fraîche. Spoon mixture into pans, using wet fingers, press down very firmly on the surface to compact the mixture in the pan. Cover, refrigerate 2 hours or until firm.
3.Preheat oven to 180°C (160°C fan forced).
4.Grease and line an oven tray with baking paper. Place peaches, cut-side up on tray, sprinkle with brown sugar. Roast for 20 minutes or until tops caramelise. Peel away peach skins.
5.Invert ricotta cakes onto serving plates, carefully peel away muslin. Drizzle ricotta cakes with honey, top with pistachios. Serve with warm or cooled peaches and toasted brioche.
To tell if a peach is ripe, look around the stem of the peach, the absence of green skin plus a strong peach aroma indicates ripeness. If the skin is slightly green, it is not ripe. If peach stones are difficult to remove, leave them during roasting, they will come out more easily after cooking. Substitutes Try roasted figs, pears and plums or fresh raspberries, blackberries and strawberries instead of peaches. Do ahead The ricotta cakes can be made up to 2 days ahead. You will need to buy a 50cm square of muslin available from kitchen and fabric supply stores.