1 small to medium onion

4 tablespoons olive oil (divided)

4 tablespoons butter

3 large cloves garlic

Salt

1 teaspoon Calabrian chili paste OR 1/2 teaspoon crushed red pepper flakes

1 cup vodka

1 can (28 ounces) Italian crushed tomatoes

A few leaves of basil, torn, plus a few to serve

1 pound penne rigate pasta

1 pound large raw shrimp, deveined and tails removed

1 lemon

1/4 cup Pernod or white vermouth

A handful flat-leaf parsley, finely chopped

1 cup heavy cream

A handful freshly grated Parmigiano-Reggiano cheese

Place a large pot of water on the stove for pasta. Also put up a deep skillet for sauce and a nonstick skillet for shrimp.

Gather your ingredients.

Peel and finely chop the onion.

In a large deep skillet, heat 2 tablespoons olive oil, a turn of the pan. Add 2 tablespoons butter and when it foams add the onions. Stir to soften while you peel and chop the garlic. Add 2 cloves of chopped garlic to onions and season with salt. Stir in 1/2 teaspoon of chili paste or about 1/4 teaspoon of red pepper flakes. Add vodka and reduce by half, 2 to 3 minutes. Add tomatoes and tear in a few leaves of basil. Reduce heat and simmer sauce, 10 minutes.

Season pasta water with a fat tablespoon of salt, add penne and cook 1 minute less than package directions, about 8 minutes. Have a mug or measuring cup on hand.

Add shrimp to a medium bowl and toss with remaining garlic. Thinly slice a lemon and toss with shrimp.

In the second skillet, heat 2 tablespoons olive oil, 2 turns of the pan, over medium-high and melt in 2 tablespoons butter. Add the shrimp mixture and toss 2 to 3 minutes; shrimp should be just pink and opaque - they will finish cooking in the pasta at the end. Add a splash of Pernod or vermouth, the remaining red pepper flakes, a little salt and parsley; toss. Turn off heat.

Add cream to sauce and stir. Bring back to a bubble and turn off heat.

Reserve about 1/2 cup of starchy salty water and drain pasta or transfer to sauce with a spider. Toss pasta with sauce and grated cheese, using water to loosen as necessary. Add shrimp to sauce.

Transfer pasta to large serving bowl or to individual shallow bowls to serve.