Prepare the Chocolate Mixture: In a saucepan, add the condensed milk, cream, and chopped semi-sweet chocolate. Mix well and heat over medium heat until the chocolate melts, stirring continuously. Bring to a gentle boil and let it cook for about 5-10 minutes until thickened.
Layer the Biscuits: Take a mold with a removable or silicone bottom and layer half of the cornstarch biscuits at the bottom of the dish. Ensure they are evenly distributed.
Add Brigadeiro Layer: Pour half of the chocolate mixture over the biscuits and spread evenly.
Repeat: Add another layer of biscuits followed by the rest of the chocolate mixture.
Chill: Place the mold in the freezer and chill for at least 2 hours or until set.
Decorate: Once set, remove from the mold, decorate with chocolate shavings and chopped biscuits, and serve!