Invite friends to make the toppings for an indulgent ice-cream potluck party—peanut brittle mixed with crispy rice cereal, fresh blueberry sauce and an over-the-top mix of crushed chocolate-covered pretzels, cookie crumbs and more.
In a medium saucepan, mix the blueberries with the sugar. Cook over moderate heat until the blueberries begin to burst, about 5 minutes. Remove from the heat. Transfer 1/2 cup of the blueberries to a blender and puree; scrape the puree back into the sauce. Stir in the lemon juice and salt and serve the sauce warm.