Combine 1 package raspberries, sugar, and juice in a small saucepan over medium-high heat; bring to a boil. Reduce heat, and simmer 8 minutes, stirring occasionally to break up berries. Place raspberry mixture and remaining package raspberries in a medium bowl; cool 5 minutes in freezer.
Place 2 tablespoons yogurt in each of 4 glasses. Top each serving with 3 tablespoons raspberry mixture and 1 1/2 teaspoons chocolate shavings. Repeat procedure with remaining 1/2 cup yogurt, 3/4 cup raspberry mixture, and 2 tablespoons chocolate.
While the different parts of the recipe are good in themselves, the proportions in which they are combined are not ideal. Note that there are 3 tablespoons of raspberry sauce to 2 tablespoons of ice cream, so it's overwhelmingly a raspberry dessert with a little vanilla and a smidgen of chocolate. I actually think parfaits are tastier with the ratios inverted, ie more vanilla, less topping. Also the chocolate is virtually indistinguishable, which is a shame because it's such a great foil for vanilla and raspberry. It either needs to be omitted or increased to get the full benefit of the flavor. Of course these changes would affect the calorie count but it is a little more honest. Also, while the sauce is great, it would be better if strained through a sieve to get the seeds out, if you have the time. If not, with the seeds works, it's just annoying. If made with the changes I suggested I would rank the recipe higher, but I'm ranking it based on making it as written.