The ripe banana is the key to creaminess – it doesn't taste like banana but adds natural emulsifiers. Use full-fat coconut milk from a can; light coconut milk makes the texture icy. If using a regular blender, let frozen fruit rest 10 minutes before blending to avoid motor strain. Store leftovers in the freezer for up to 2 weeks; let sit at room temperature 15 minutes before serving, or re-blend with a splash of coconut milk. Taste the berries before sweetening – some batches need more or less agave.