1. Peel the shallots and garlic. Cut the shallots into half-round slices. Mince the garlic.
2. Clean and remove the seeds from the chili pepper, then finely chop the flesh.
3. Remove the stems from the tomatoes and roughly chop the flesh.
4. Cook the spaghetti al dente in salted water according to the package instructions. Drain them and mix them with a drizzle of olive oil.
5. Heat a little olive oil in a saucepan. Sauté the shallots, garlic, and chili pepper for 2 minutes. Stir in the tomato paste. Deglaze with the wine and let it reduce. Add the tomatoes and simmer for 5 minutes.
6. Place the mussels in the saucepan, season with pepper and a tiny pinch of salt. Cover and cook for 4 minutes. Remove most of the mussels from their shells and put them back into the sauce.
7. Finely chop the parsley. Add the pasta and parsley to the mussel sauce and mix.
8. Preheat the oven to 200°C (400°F).
9. Cut the ciabatta into 2 cm (0.8 inch) slices. Arrange them on a baking sheet lined with parchment paper. Toast them in the oven for 8 to 10 minutes.
10. Spread a small amount of herb butter on each piece of bread and let it melt.
11. Serve with the pasta and mussels. Garnish with basil leaves and mussels in their shells.