On a clean work surface mound the flour and create a large well in the center using a fork.
Crack the 3 eggs into the well, add 1/2 tsp salt and 1/2 tsp olive oil, then beat with a fork while gradually incorporating flour from the sides until a dough begins to form.
Use your hands or a bench scraper to bring the dough together; adjust with a little more flour if sticky or a splash of water if too dry.
Knead the dough for 8–10 minutes until smooth and elastic, wrap in plastic wrap, and let rest about 20 minutes.
While the dough rests, make the filling: in a bowl combine 1 cup ricotta, 1/8 lb finely grated Parmigiano Reggiano, 1 egg, 2 tbsp chopped basil, and salt and pepper to taste; stir until smooth and set aside.
Flour a baking sheet and set aside. Unwrap the dough and divide into four sections, keeping unused sections wrapped so they don't dry out.
Roll one section of dough on a floured surface with a floured rolling pin, working from the center to the edges until it is very thin and long, rotating to prevent sticking.
Place small mounds of filling (about 1 teaspoon each) on the rolled dough spaced about 1½–2 inches apart, taking care not to overfill.
Fold the dough over the filling, press around each mound to remove air, then use a floured ravioli stamp or cutter to cut out ravioli; transfer to the floured baking sheet.
Gather leftover dough scraps into a ball, wrap and let rest, then continue rolling, filling, and cutting until all ravioli are made.
To freeze, place trays of ravioli in the freezer for 24 hours, then transfer to freezer bags (optional step).
Bring a large pot of salted water to a boil, add ravioli and stir gently; they are done once they float to the top.
Reserve about 1/2 cup pasta water, then drain the ravioli and return them to the hot pot off the heat.
In a small saucepan melt 2 tbsp butter, grate or add 1/2 clove minced garlic, then stir in 1/4 cup heavy cream and 3/4 cup finely grated Parmigiano Reggiano; season with salt and pepper.
Cook the sauce 1–2 minutes until it thickens slightly, adding reserved pasta water as needed to reach desired consistency, then toss with the ravioli and serve garnished with chiffonaded basil if desired.
