In a pot, melt butter and add mini marshmallows. Stir until melted. Then stir in the rice krispies.
Line a greased 4x6 container or dish with half of the rice crispy mixture. Chill in the freezer for about 5 minutes or until slightly hardened.
Working quickly, use a spatula to layer some ice cream on top. Be sure to smooth out and spread onto the edges. Place back in the freezer for another 10-15 minutes.
If the rest of the rice crispies have hardened, heat the pot on low and remove when pliable again. Using wet hands, spread the remaining mixture onto the ice cream layer. Chill in the freezer for a few hours until set.
Melt the chocolate in a bowl.
Slice the ice cream sandwiches and dip halfway in the melted chocolate. Place in the freezer to chill until set.