The Cake

• Stir together the flour, sugar and yeast in a large bowl. Mix the salt, milk and eggs together in a jug then pour into the flour mixture and beat well using a wooden spoon for about 5 minutes to make a thick, sticky batter.
• Gradually add the butter, beating until the mixture is smooth, elastic and shiny. Finally fold in the orange and lemon zest. Cover the bowl with cling film and leave to rise for 1 hour.
• Grease a 23cm/9in bundt tin or savarin mould with butter. When the batter has risen, spoon it into the tin. Cover with oiled clingfilm and leave to rise for 45 minutes to 1 hour, until it reaches three-quarters of the way up the tin.
• Preheat the oven to 180C/160C Fan/Gas 4.
• Remove the cling film and bake for 20–25 minutes or until the savarin rises and golden-brown. Remove from the oven and place the tin on a wire rack to cool for 5–10 minutes.
• When cool enough to handle, remove the savarin from the tin and pour half of the syrup into the tin. Gently place the savarin back into the tin to soak up the syrup and cool completely. Pour the remaining syrup into a roasting tin, then place the savarin into the syrup and leave to soak for 5 minutes. Carefully transfer to a serving plate.

For the syrup

For the syrup, tip the sugar into a pan, add the lemon juice and 5 fluid ounces of water and bring to a simmer, stirring until the sugar dissolves. Remove from the heat, stir in the orange liqueur and leave to cool.

For the caramel shards, line a baking tray with silicone or baking parchment. Add the sugar to a pan with 4 tablespoons water and bring to a simmer, stirring until the sugar dissolves. When all the sugar is dissolved, bring the syrup to a boil without stirring until it reaches 170C on a sugar thermometer (CAUTION: boiling sugar is extremely hot. Handle very carefully). Immediately pour out onto the lined tray and leave to harden. Crack with a spoon or cut into shards using a knife.

• Using a sharp knife, segment the zested orange. Carefully slice off the top and bottom of the orange. Using even downward strokes, slice the skin away from the flesh and discard. Remove any remaining white pith.

For the Caramel

• Line a cookie sheet with parchment paper.
• Place cold water and ice in a pan. This will be used for later and will stop the syrup from burning.
• Place sugar and lemon juice in a double boiler. Put water in the bottom pan but make sure the top pan doesn't touch the water.  Also, have a little glass of water and a brush to clean off the sides of the pans of sugar crystals throughout this process.
• Bring water to a boil over medium-high heat. Stir syrup until mixture turns color around 5-8 minutes.
• Once it turns color stir and cook for another 30 seconds. 
• Quickly take off stove and place in a pot of cold water and ice. This stops the cooking of the syrup. 
• Place the hot mixture on the parchment paper and spread like a sheet. Cool and break in pieces.

Constructing the Cake

Place cake on stand. Fill middle of the bundt with sabayon filling.

• Place fruit in the top along with caramel shards.
• Pipe sabayon around the cake.