Place the chocolate chips in a microwave safe bowl. Microwave until softened (about 30 seconds). Stir until melted. Add the condensed milk to the melted chocolate and mix well. Add the chocolate pudding mix and milk. Stir everything together well. Refrigerate for an hour. Add heavy cream to a bowl. Whip the cream with a hand or stand mixer until it forms stiff peaks. Fold the chocolate mix into the whipped cream until incorporated, but don’t overmix. Spoon mousse into small jars filled 1/2-3/4 of the way to the top. Refrigerate 3 hours or overnight.