Start with very soft dates for the best results. The bars are best served very cold, just out of the freezer; make them in advance for a special party, and store extras for up to three months in the freezer. Be sure to use raw, not roasted, cashew butter for the best color and flavor; or soak 1/4 to 1 cup of raw cashews for six to eight hours, rinse, drain well, and process in a food processor with the rest of the filling ingredients.
Visit betternutrition.com and search “plant proteins” for more information, including how pea protein stacks up against other vegetarian protein sources.
- Cut parchment to fit width of an 8-inch-square glass baking pan, leaving a 2-inch overhang on both sides. Combine dates, walnuts, and salt in a food processor; process 2–3 minutes on high speed until mixture is pasty and holds together when pressed with your fingers. If mixture is dry, add 1–2 tsp. water. Add protein powder, and process 30 seconds longer, until well-blended. Press mixture evenly into bottom of prepared pan, and place pan in freezer while preparing filling.
- In medium bowl, beat together cashew butter, yogurt, agave or honey, and lemon juice. Spread over crust in baking dish with rubber spatula, and smooth top. Transfer to freezer, and freeze 3–4 hours, until very firm.
- Rinse food processor well, and add blueberries, chia seeds, and agave or honey, if using. Pulse briefly to mix; mixture should be chunky. Set aside (mixture will thicken as it stands).
- To serve, remove lemon-cashew bars from freezer. Run butter knife around edges that touch the pan directly. Using overhanging parchment as a sling, lift bars from pan and carefully peel off parchment. Transfer to cutting board, spread with blueberry mixture, and cut into 12 squares. Serve immediately.