In a medium saucepan, pour in milk and add salt, cocoa powder, and sweetener. Warm over medium heat, stirring until dissolved, about 2–3 minutes.

In a separate bowl, whisk together additional milk and cornstarch until smooth. Set aside.

Whisk the cornstarch mixture into the warm milk mixture, increase heat, and stir until it thickens, about 2 minutes.

Reduce heat, stir in vanilla extract, and optional chocolate until melted.

Transfer to serving dishes, cover with plastic wrap, and refrigerate for several hours or overnight.

Serve chilled, topped with coconut whipped cream or fresh fruits.