Heat the oven to 180C/fan 160C/gas 4. Put the figs, cut-side down, into a 20cm x 30cm baking dish. Whisk together the amaretto, caster sugar, ½ tsp vanilla and 50ml of water in a small pan and heat until the sugar dissolves, then pour over the figs. Cover the dish with foil and roast for 10 minutes, before removing the foil and roasting for another 15 minutes. Cool to room temperature.