300 degree oven. Line a 9 x 13" pan with foil, extending a little over the edges of pan. Place Rice Krispies, coconut, and brown sugar in a 9 x 13" pan. Drizzle butter over mixture and combine well (a fork or clean hands work well). If desired, sprinkle a few shakes of cinnamon and mix in. Bake for about 30 minutes, stirring once or twice during cooking time. Remove from oven when toasted and golden brown and let mixture cool completely.
Remove half of crispy mixture and spred remaining half in an even layer on the bottom of pan. Gently spoon softened ice cream on top of mixture. Use a spoon and very gently spread mixture, being careful to not lift up crisp from bottom of pan. Spread ice cream out evenly and then top with remaining crisp mixture. Gently press top crisp into ice cream with hands. Cover pan with plastic or foil and chill until firm (preferably overnight). When ready to serve, use foil to completely remove ice cream from pan. Slice into squares and serve. ENJOY!!!