• Place the dates in a medium bowl and cover with purified water. Let them soak while you follow the next few steps. Make sure your dates are very fresh, soft, and moist; if they’re not, soak them for several hours.
  • Preheat the oven to 350°F.
  • Spread the walnuts and hazelnuts on a baking sheet, place it in the oven, and toast the nuts for 10 minutes. Remove from the oven and let cool. Meanwhile, spread the sunflower seeds on a separate baking sheet and toast them for 5 minutes. Remove from the oven and let cool. Rub the toasted walnuts and hazelnuts with a kitchen towel to remove their skins.
  • Pulse the rolled oats in a food processor to partially grind them, about 10 pulses. Transfer into a large bowl. Add the walnuts, hazelnuts, sunflower seeds, Brazil nuts and salt to the food processor and grind to the consistency of breadcrumbs. Drain the dates, remove the pits, and add to the nut mixture in the food processor, along with the maca powder, if using, the coconut butter, and tahini. Grind until well combined and as smooth as possible.
  • Add the remaining ingredients to the large bowl with the rolled oats, followed by the nut-date mixture. Using your hands, combine everything very well. The mixture should be sticky and hold together when pressed between your fingers.
  • Line an 8 × 8-inch baking pan with parchment paper extending up the sides. Press the mixture into the pan in an even layer and freeze for 1 hour. Remove the pan from the freezer, lift the halva out with the parchment paper, and place the halva on a cutting board. Carefully slice it into bars with a large, sharp knife. It will keep refrigerated in an airtight container for up to 3 weeks. You can also store the bars in the freezer; they don’t harden completely, so you can eat them straight from the freezer.