"Create a fun dessert shake recipe titled 'Tera — Sour Blueberry Stretch-Up Beatbox Shake' featuring blueberry purée, vanilla ice cream, a small amount of sour-candy flavoring, lavender-flavored syrup, and a stretchy marshmallow topping. Finish with blueberries and crushed sour candy for a purple-and-electric-blue appearance. Make it visually striking, sweet-tart, and suitable as a thick milkshake. Use imperial units."