1. Preheat your oven to 160c.
2. Toast the brown bread in a toaster until slightly charred.
3. Spread the butter on the toast and place in the oven until the toast is dry, about 5 minutes. Remove the toast from the oven and leave to cool.
4. When the toast has cooled, place in a food processor, until you have fine crumbs.
5. Cook the pasta in a large pan of salted water (see packet for cooking times).
6. While you are waiting for the pasta to cook, heat the olive oil with the garlic and chilli flakes on a medium heat until the garlic is slightly toasted. Add the anchovies and butter, once the butter has melted add the lemon juice and zest and remove from the heat.
7. Once the pasta is cooked, drain well, reserving some of the pasta water.
8. Put the pasta back in the pan and add the garlic, chilli, and lemon butter, the caviar and half of the dill.
9. Season with salt and pepper and add a ladle full of the reserved pasta water, then toss well.
10. Divide between 4 warm bowls, and sprinkle with the remaining dill and brown butter crumbs. Serve straight away.