Steam broccoli and soak cashews in boiling water for at least 15 minutes.
Cook pasta in salted water according to package instructions and reserve 1/2 cup of pasta water to blend with the pesto later.
Process all ingredients for the pesto in a small processor. Set aside ~ 1/3 cup of pesto and blend the rest with the 1/2 cup of reserved pasta water.
For the walnuts, add olive oil to a small pan and saute crushed walnuts for a few min. Then add lemon zest and minced garlic. When the walnuts are almost perfectly toasted, sprinkle in 1/2 tsp dried sage a minute before taking the pan off of the heat.
Pour the sauce over the pasta, combine well, and top with those walnuts!