In a large pan over medium-high heat, add the olive oil and chopped white onion. Fry for 5 minutes and then add the anchovies, no need to chop as they melt into the sauce. Once soft and the anchovies melted away, stir in the garlic, capers, anchovies, and basil stems, chopped. Cook for a further few minutes.
Meanwhile, boil the pasta in salted water according to package instructions.
Add the tinned tomatoes and a splash of water, and simmer for 5-7 minutes, until thickened a little.
Taste and adjust seasoning. Once the pasta is cooked, reserve a mug of pasta water, drain the rest and add to the sauce directly.
Toss together until a gorgeous sauce forms and coats each pasta. Add splashes of water as needed to make sure it doesn't thicken too much, you want it nice and saucy. Tear in the fresh basil leaves and add a good grating of parmesan.
Scoop into bowls, top with more parm and burrata if using. Enjoy!