In a small bowl, whisk the cocoa powder, granulated sugar, corn starch, and salt together.
1/4 cup cocoa powder, 1/4 cup granulated sugar, 1 tbsp cornstarch, 1/4 tsp salt
Pour the dry ingredients into a medium saucepan, top it all with the milk, and cook on the stove on medium heat stirring constantly.
1 cup milk
Once the mixture is thick, remove from the heat, add in the vanilla extract and the semi-sweet chocolate, and mix until the chocolate is fully melted and combined.
1/4 tsp vanilla extract, 1/4 cup semi-sweet chocolate chips
Let the mixture cool down fully before pouring it into a popsicle mold and freeze for 4 hours or overnight before enjoying.