In a medium, heavy-bottomed saucepan, heat passion fruit purée and butter over medium heat, stirring occasionally, until simmering. In a medium bowl, whisk sugar and yolks together to form a paste. Slowly add hot liquid, whisking constantly, until combined. Pour mixture into pan and cook, whisking constantly, until it just reaches a simmer around the edges, about 4 minutes. Transfer to a glass or ceramic bowl, cover with a piece of plastic wrap pressed against the curd's surface to prevent a skin from forming, and chill until cold and firm, about 1 1/2 hours.
Using an electric mixer, whisk cream until soft peaks form. Whisk in one-third of the cold curd; then, using a rubber spatula, fold in the remaining curd. Put 3 or 4 brownie chunks into the bottom of an 8-oz. juice glass or other serving dish of similar size. Top brownies with about 1/4 cup passion fruit cream, another 3 or 4 brownie chunks, then another 1/4 cup cream. Repeat with 11 more glasses. Chill until ready to serve.
Heat chocolate sauce in microwave until it is warm and easily drizzles off the back of a spoon. Spoon about 1 tbsp. chocolate sauce over each parfait and serve.
*Find passion fruit purée in the freezer section of most well-stocked grocery stores. You can either buy the brownies and chocolate sauce or make them yourself (see sunset.com for recipes).
Make ahead: You can make the passion fruit cream and assemble the parfaits 1 day ahead. Add chocolate sauce at the last minute.
Note: Nutritional analysis is per serving.