For the Lemon Curd, place a medium saucepan half filled with water over a low heat and bring to a simmer. Combine all ingredients in a medium sized bowl. Sit the bowl over the saucepan of simmering water and whisk continuously until mixture thickens. Remove from the heat and allow to cool. Transfer to a piping back and set aside in the fridge.
For the Chantilly Cream, combine all ingredients in a medium bowl and whisk until fully combined and thickened. Transfer to a piping bag and set aside in the fridge.
For the Sweet Potato Beignets, place a medium saucepan of water over high heat and bring to the boil. Add sweet potato and boil until tender, about 12-15 minutes. Remove from the heat and drain. Return potato to the saucepan.
Add 25g of the butter to the potato and mash until smooth. Pass through a fine sieve, season and set aside.
Place 100ml water and remaining 25g butter into a small saucepan and place over low heat until butter has melted. Add flour and stir until a thick paste is formed and dough pulls away from sides of the saucepan.
Transfer to a stand mixer fitted with a paddle attachment and mix on medium speed to release heat from the mixture, about 2-3 minutes.
Add the eggs, one at a time, and beat well after each addition. Fold in the mashed sweet potato then season to taste. Transfer dough to a piping bag.
Oil a soup spoon with a little oil to grease. Snip the tip of the piping bag of dough and pipe golf ball sized amounts of dough onto the greased spoon and carefully slip dough balls from spoon into the deep fryer. Fry until golden brown, about 7-8 minutes. Remove from the fryer and drain oil on paper towel.
To serve, place Sweet Potato Beignets onto a serving plate and dust with icing sugar. Pipe Chantilly Cream and Lemon Curd around plate and serve.