To prepare a Tom Kerridges lemon and rosemary polenta cake recipe, you will first need to prepare the following ingredients: 1 cup (240 ml) boiling water 1 tablespoon (15 g) lemon zest 1 teaspoon (0.5 tsp) rosemary 2 tablespoons (60 milliliters) granulated sugar 2 teaspoons (1.25 oz) vanilla extract Instructions: Preheat the oven to 180oC/350oF. Grease and flour two 8-inch round cake pans and set aside. Sift the flour, baking powder and salt into the bowl of the electric mixer fitted with the whisk attachment. Add the butter and beat until the mixture is light and fluffy, about 2 minutes. Gradually add the milk, beating well after each addition. Slowly stir in the sour cream and vanilla. Beat the batter until it is thick and glossy, but not runny. Spoon the lemon mixture evenly over the cake batter. Bake for 35 to 40 minutes or until browned. Serve warm or at room temperature.