The Sonic website says it's topped with hazelnut flavor and whipped topping (redundant I know, but that's what happens when a chain doesn't spring for real whipped cream), but mines wasn't topped with any hazelnut flavor. Still, the drink has plenty of hazelnut flavor blended in so it's more of an aesthetic thing than anything.
This drink made me decide that I don't really like hazelnut flavor that much. I think it's more like I like the idea of hazelnut flavor. The ice cream was fairly thick and creamy, the coffee was apparent, and the hazelnut was pretty strong. Basically, Sonic's Hazelnut Java Chiller is great if you like coffee flavor, thick shakes, and hazelnut. As for me, I think from now on, I'll just kick it old school with a plain Java Chiller.
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Nutritional Info - Regular Hazelnut Java Chiller (305g)
Calories - 493 (from Fat - 214)
Fat - 24g (Saturated Fat - 17g)
Sodium - 263mg
Carbs - 64g (Sugar - 60g)
Protein - 7g