Combine ingredients into a food processor or high-speed blender.
Pour into a pan and smooth into an even layer.
Freeze for 2 hours, or until frozen but still a little soft for scooping. (If freezing overnight, cover with a lid or plastic wrap, but let it sit out at room temperature for about 5-10 minutes before scooping).
Scoop into a bowl and top with frozen raspberries and lemon zest.
Conversion: 1 metric cup = 250ml. 1 Tbsp = 15g.