Try adding some cubed eggplant. The eggplant melts into the sauce. Anchovies are also good in pasta sauce, you would never know they were never, but they make a big difference.
Last year I grated the yellow squash into my potatoes and leeks and frozen cauliflower before par boiling. Before the potatoes were completely cooked, I drained everything, added S&P to taste, coarsely grated Guyere cheese, a tiny bit of milk (1/4 c) and gently mashed adding an egg at the end...