Bring a large pot of water to a boil, and salt it liberally.
Meanwhile, heat 1 tablespoon each olive oil and butter in a sauté
pan over medium heat. Add the onions, anchovy, garlic, thyme, and bay
leaf. Season lightly with salt, and cook over medium heat until the
onions are caramelized, 15 to 20 minutes, stirring often. Remove the
thyme stems and bay leaf and discard.
Meanwhile, cook the pasta until it is al dente. Reserve the pasta
water.
Toss the pasta with the remaining butter and olive oil, and the
onion mixture, and moisten with pasta water as needed. Top with the
chopped olives, lemon zest, and some fresh thyme leaves.