1. Grease a 23cm (9in) round cake tin. To make the topping, heat the butter, syrup and sugar in a saucepan over a medium heat, stirring until the sugar is dissolved, then pour into the base of the tin. When cool, arrange the pecans (rounded sides down) in concentric circles in the topping mixture.
2. Heat the oven to 170°C (gas mark 3). To make the cake, beat the butter and caster sugar for 3-4 minutes, until pale and fluffy. Add the egg yolks, one at a time, beating well after each addition. Fold in half the flour, a pinch of salt, then half the milk and continue to do this gradually until smooth. Stir in the coffee, vanilla and nuts.
3. Beat the egg whites until they form stiff peaks, then fold into the cake mixture. Pour the batter into the tin over the pecans and topping.
4. Bake for about 50-60 minutes or until firm to the touch and an inserted skewer comes out clean. Cool in the tin for about 15 minutes, then turn out onto the plate to cool completely.