Prepare Pan: Line a 9×13 inch pan with parchment paper or grease well with cooking spray.
Mix Dry Ingredients: In a bowl, combine strawberry gelatin powder, vanilla pudding mix, and flour. Set aside.
Melt Marshmallows: In a large pot over medium heat, melt butter. Add marshmallows and stir constantly until completely melted and smooth, about 3-4 minutes.
Add Creamy Ingredients: Remove from heat. Stir in vanilla essence and marshmallow cream until well combined.
Add Powder Mixture: Quickly stir in the dry ingredient mixture until evenly distributed and pink color spreads throughout.
Mix in Cereal: Add crispy rice cereal and fold gently until all cereal is coated with the marshmallow mixture.
Press Into Pan: Transfer to prepared pan. Use buttered hands or parchment paper to press mixture down evenly and firmly.
Cool and Set: Let cool at room temperature for 30 minutes or refrigerate for 15 minutes until firm.
Cut and Serve: Lift from pan using parchment paper. Cut into 16 squares with a sharp knife.