Drizzle some olive oil in a large pot of boiling salted water, add the spaghetti and cook al dente. Drain quickly, leaving a little water with the spaghetti. Quickly toss the spaghetti with the melted butter, lemon zest, lemon juice, salt and pepper.
Place one serving of pasta on each plate and top with a large dollop of fresh caviar. Garnish with grated lemon zest. Serve immediately.