1. Clean the crabs if you haven’t already (instructions below), or leave them whole if that’s how your family does it. Rinse and pat dry with paper towels.
2. Heat olive oil in a large, heavy-bottomed pot over medium-high heat.
3. Saute the crabs until they turn bright orange, about 2-3 minutes, then remove to a plate. 
4. Add the garlic and red pepper flakes to the pot. Cook gently until the garlic is fragrant and just starting to turn golden, about 1-2 minutes. Don’t let it brown.
5. Add the tomatoes. Crush them by hand as you add them to the pot, or use a wooden spoon to break them up. Add a big pinch of salt. Bring to a simmer.
6. Nestle the crabs into the sauce, shell side down. Cover the pot and reduce the heat to low. Simmer for 1½ to 2 hours, stirring occasionally and making sure the crabs stay mostly submerged. The sauce will deepen in flavor and take on a rich, briny sweetness from the crabs.
7. In the last 10 minutes, stir in the torn basil. Taste the sauce and adjust salt as needed.
8. Meanwhile, boil the pasta in salted water until al dente. Drain and set aside.
9. Serve the pasta topped with the crab gravy, and pile the crabs on a platter alongside (or right on top). Drizzle with a little extra olive oil and scatter a few more basil leaves if you like.

How to Clean a Live Crab

1. If you're starting with live crabs, the first step is to humanely dispatch them. The most common way is to place them in the freezer for about 15-20 minutes, or in ice water for 5-10 minutes, to gently sedate them. Once they’re still, it’s time to clean.
2. Hold the crab belly-side up. Using a sharp knife or ice pick, quickly pierce the small triangular flap (called the apron) in the center. This kills the crab instantly and is the most humane method. Alternatively, you can boil it for 30 seconds to a minute, just enough to kill but not fully cook.
3. Flip the crab over and pull up the apron. Tear it off and discard.
4. Turn the crab right-side up. Grip the shell from the back and lift it off—it should pop right off with a bit of pressure. Set it aside or discard.
5. You’ll see feathery gray gills on either side. Pull those off and discard. Scoop out the yellowish or greenish guts (technically called "viscera" but we call it "mustard") with your fingers or a spoon.
6. Give the crab a good rinse under cold water to remove any remaining debris. If you want to break it down further, snap the body in half or into quarters for easier cooking and eating.
7. Cook immediately after cleaning to ensure the texture isn't compromised.