Line an 8 x 8 pan with foil.

Place the dark chocolate chips in a microwave safe bowl and the white chocolate chips in another microwave safe bowl. Add 1/4 cup of sweetened condensed milk to the white chocolate chips and the remaining sweetened condensed milk and cinnamon to the dark chocolate chips.

Melt the dark chocolate chips and sweetened milk in 30 second intervals, stirring after each heating, until completely melted. Pour in the prepared pan.

Melt the white chocolate chips and sweetened milk in 30 second intervals, stirring after each heating, until completely melted. Pour on top of the dark chocolate.

Immediately pour the mini marshmallows on top of the white chocolate and press them into the chocolate.

Refrigerate for 2 hours. Cut into 2 inch squares.