Preheat the oven to 180°C, 160°C fan, Gas Mark 4.
Place the pears in a roasting tin, drizzle with the wine and oil and sprinkle with the sugar. Roast for 45 minutes, turning occasionally, until tender and starting to caramelise. Allow to cool to room temperature. Meanwhile, to make the cake, lightly grease an 11 x 22cm loaf tin, and line the base and sides with nonstick baking paper. Beat the sugar and eggs together in a large bowl with an electric mixer until pale and creamy.
Add the oil, wine, milk and lemon zest and beat until well mixed. Add the sifted flour and baking powder and slowly beat until just combined. Pour the mixture into the prepared tin. Bake alongside the pears for 40 minutes, or until a skewer comes out clean when inserted into the middle of the cake. Allow to stand for 5 minutes before turning out onto a wire rack to cool completely. Meanwhile, to make the wine syrup, place the sugar and 2 tbsp water in a small pan and stir constantly, over a very low heat, without letting it boil, until the sugar has completely dissolved.
Increase the heat and allow the syrup to simmer, brushing the side of the pan with a wet pastry brush if necessary, until the syrup turns a golden colour. It is important to keep an eye on the syrup at all times, as once it starts to colour, it will continue to darken very quickly. Turn off the heat, add the wine and stir to combine. Some of the syrup may solidify at this point. If this is the case, return it to a very low heat until it dissolves again. Set aside to cool. Serve the cake with the pears, drizzle with the syrup and add a dollop of crème fraïche.