Soak almonds and cashews overnight for the smoothest crust and creamiest filling. Blend the cashew cream for at least 2 full minutes. Stir in poppy seeds, raisins, and psyllium by hand after blending. Line the tin with cling film before pressing in the crust for easy unmoulding. Set overnight for the cleanest slices. Keeps refrigerated for 4 days; freezes well for up to 2 months.