1) 2 heaping cups fresh basil leaves, stems removed
2) 2 large cloves garlic
3) 1 heaping T Dijon mustard
4) juice of 1/2 lemon
5) 1 egg yolk
6) 2/3 c good quality extra virgin olive oil
7) 1 t salt
8) freshly ground pepper
Process 1) & 2) to puree.
Add 3) to 5) till smooth.
Pour in 6) while running till thick.
Season, chill.