Clams Arrabbiata

Cook oil and pancetta in a medium Dutch oven over medium heat, stirring occasionally, until pancetta begins to crisp, about 5 minutes. Add onion and cook, stirring occasionally, until softened but not browned, 6–8 minutes. Add garlic and cook, stirring occasionally, until softened and fragrant, about 5 minutes. Stir in red pepper flakes.
Add tomatoes, crushing with your hands as you go; increase heat to medium-high. Bring to a simmer and cook, stirring often, until tomato liquid is reduced by half and tomatoes take on a jammy consistency, 12–15 minutes. Add clams and 2 cups water. Cover pot and cook, stirring occasionally and reducing heat as needed to maintain a simmer, until clams begin to open, 8–10 minutes. Uncover pot and transfer opened clams with a slotted spoon to a plate. Re-cover pot and continue cooking clams until they open, up to 15 minutes longer; discard any clams that haven’t opened by this time.
Add ditalini to pot and cook, stirring often (pasta will want to settle and stick to the bottom of the pot), until al dente, 8–10 minutes. Add clams back to pot.
Ladle clams and sauce among bowls; top with basil. Serve with bread alongside for dipping.