Heat the olive oil in a large skillet over medium heat.
Add the Italian sausage and cook, breaking it up into crumbles and stirring often, for 3 minutes.
Add the grape tomatoes, shallot, and crushed red pepper flakes then cook, stirring often, for 2 minutes.
Add the minced garlic and cook, stirring constantly, for 30 seconds.
Add the canned tomatoes and lower heat to low; simmer for 30 minutes, stirring occasionally while making sure to break up the canned tomatoes with the spoon.
Taste and season with sea salt and freshly cracked pepper, to taste.
Cook the gnocchi in salted boiling water, per package instructions, about 3 minutes; drain, reserving 1/4 cup of cooking water.
Add the drained gnocchi to the tomato sauce and a bit of the cooking water if needed.
Add the fresh baby spinach and toss to coat evenly.
Pour into a baking dish and top with pieces of ripped mozzarella (or shredded is fine too). Place into the oven and bake for 10 minutes. If you want to brown the cheese, place the baking dish under the broiler for a minute or two - watch it carefully so it doesn't burn!
Remove from the oven and allow it too cool for a few minutes.
Add the fresh basil to the top and serve with Parmesan on the side. Enjoy.