Preheat oven to 350ºF. Combine chocolate and 3 Tbsp. water in a microwave-safe bowl. Microwave on high just until chocolate is melted, 30 seconds to 1 minute. Whisk until sauce is smooth. Set aside to cool slightly.
Using an electric mixer on medium-high speed, beat cream and confectioners' sugar until firm peaks form.
Put croissants on an ungreased baking sheet and bake until warm and lightly crisped, about 4 minutes. Cut each croissant in half; split each half lengthwise. Place bottoms of croissant halves in dessert bowls. Scoop ice cream on top. Drizzle with warm chocolate sauce and top with a dollop of whipped cream. Place croissant tops over ice cream and sauce. Serve immediately.