In a 12-inch skillet over medium-high heat, add the oil.
Add the gnocchi and cook, undisturbed, for 3 to 5 minutes, until a golden crust has formed on the bottom of the gnocchi.
Stir the gnocchi. Add the shallot and cook, stirring frequently, for 3 minutes.
Add the peas, zest and juice of 1 lemon and the pesto. Stir to combine.
Taste and season with salt, if needed (some pesto sauces are on the saltier side, so you might not need extra salt).
Dollop the ricotta on top. Top with the grated mozzarella.
Place the skillet underneath the broiler and broil for 4 to 5 minutes, until the cheese is completely melted.
Top with more pesto, if you like and serve right away.
