Well, this wasn't a failure, but an interesting detour. Mushroom stems are rather fibrous and don't process down all that well. However, once I got the Hummus through the sieve, it was wonderful.
Recipe: Roasted Garlic and Mushroom Hummus
1 can Garbanzo Beans, drained, reserve the liquid
2 teaspoons tahini paste
2 cloves roasted garlic
1/2 cup browned mushrooms
2 teaspoons olive oil, divided, reserving one teaspoon oil for top of hummus.
Process the above ingredients in a food processor until smooth, use some of the reserved liquid from the can of beans if needed. Drizzle one teaspoon of olive oil over the top before serving.