Place a large skillet with a lid over medium-high heat and add the olive oil. Bring a large pot of salted water to the boil.
Lightly rinse the shrimp to help separate them and remove any large pieces of ice. Shake off any excess water, then toss the shrimp with the lemon pepper seasoning.
Add the shrimp to the hot oil, using tongs to move into a single layer. Cover and let cook until the shrimp start to defrost and turn pink, about 2 minutes. Uncover, flip the shrimp and cook for an additional 2 to 3 minutes, flipping for the final minute. Check that the shrimp are pink all over, then remove to a plate.
Deglaze the skillet with the wine, scraping the bottom. Add the cream, mascarpone, pesto, lemon zest and good pinch of salt and pepper. Stir to combine and bring to a simmer. Continue simmering for 1 to 2 minutes and allow the sauce to thicken slightly.
Add the gnocchi to the boiling water and cook for 3 to 4 minutes. When the gnocchi are ready, they will begin to float.
Drain the gnocchi and add to the sauce along with the frozen peas and the shrimp with any juices. Stir and heat through until the sauce has thickened a little more and everything is combined, about 2 minutes. Taste and adjust the seasoning as needed. Garnish with the basil and lemon slices.