Bring a medium-size pot of water to a boil. Add pearl onions and boil 3 minutes. Drain, cool and trim root ends. Pop onions out of the skins.
Place a large pot of water over high heat for the pasta.
Heat a deep saucepan or skillet over medium heat with EVOO and butter. Add onions and garlic to skillet, season with salt and pepper. Add vodka and reduce a minute or 2. Add tomatoes and stir. Heat through then add cream and let reduce at a low, bubbling simmer while pasta cooks.
Cook pasta in boiling, salted water to al dente and drain.
Add peas and herbs to pasta sauce and stir to heat through, 1-2 minutes. Add pasta to sauce and toss 1 minute to combine. Serve pasta with grated Parmigiano-Reggiano cheese at the table.