Preheat oven to 180°C. Cut a 100g piece from pumpkin and set aside. Cut remaining pumpkin into 3cm chunks. Wrap chunks in foil and place on an oven tray, then bake for 45 minutes or until tender. Remove from foil and cool. Mash cooled pumpkin then measure 1 cup puree. Using a vegetable peeler, peel reserved pumpkin into thin, wide strips.

Place 1 cup sugar and 1/2 cup water in a saucepan and stir over medium heat until sugar dissolves. Add pumpkin strips and cook for 20 minutes or until pumpkin is translucent and syrup is thick. Using a slotted spoon, transfer pumpkin to a piece of baking paper to dry. When dry, place in a bowl and scatter with 1/2 cup sugar. Stir lemon juice into syrup and set aside.

Grease a 24cm non-stick, fluted (bundt tin) cake tin. Using an electric mixer, beat butter and remaining 1 cup sugar until light and fluffy. Gradually add egg yolks and beat until combined. Add 1 cup pumpkin puree, walnuts and rind then beat until incorporated. Sift flour and 1/2 tsp salt over then gently stir in. In a clean bowl, using an electric mixer, whisk eggwhites until soft peaks form then gently fold into pumpkin mixture. Spoon into prepared tin and bake for 45 minutes or until a skewer inserted into the centre comes out clean. Stand for 10 minutes then turn on to a wire rack over a tray.

Using a pastry brush, brush warm syrup over warm cake then top with walnut halves and candied pumpkin. Serve warm or at room temperature.