Step 1

Place a large steamer over a large saucepan of simmering water. Steam sweet potato and potato for 45 minutes or until tender (see note). Set aside until cool enough to handle. Remove and discard skin. Transfer flesh to a bowl. Mash until smooth. Season with salt and pepper. Set aside to cool completely.

Step 2

Add egg yolk and flour. Stir to form a firm dough (if too soft, add a little more flour). Turn out onto a floured surface. Knead until smooth. Line 2 baking trays with baking paper.

Step 3

Divide dough into 8 equal portions. Roll 1 portion into a 35cm-long log. Using a lightly floured knife, cut into 2cm pieces. Repeat with remaining dough portions. Roll each piece of dough into a ball. Roll each ball over a floured fork to form grooves. Arrange gnocchi between prepared trays (freeze half the gnocchi – see note).

Step 4

Make pesto Process basil, garlic, parmesan, nuts and lemon juice until finely chopped. With the motor running, add oil in a thin steady stream until combined. Season with salt and pepper (freeze half the pesto – see notes).

Step 5

Cook remaining gnocchi in a large saucepan of boiling, salted water for 3 minutes or until they rise to the surface. Using a slotted spoon, drain and transfer gnocchi to a large bowl. Add remaining pesto. Gently toss to combine. Divide between bowls. Serve with rocket and parmesan.