Prep the dish. Lightly grease a 9x13-inch glass dish with cooking spray, then wipe away excess with a paper towel so it’s just barely coated. This helps with clean slices.

Make the base gelatin. In a large bowl, whisk the strawberry gelatin with 2 cups boiling water until fully dissolved, about 2 minutes.

Cool it down. Stir in 1 1/2 cups cold water (or 1 cup cold water plus 1/2 cup ice to speed things up). Mix until the mixture is slightly cool to the touch.

Fold in the fruit. Gently add the sliced strawberries and well-drained crushed pineapple. If using mini marshmallows, sprinkle them in now. Stir to distribute evenly.

Set the first layer. Pour the mixture into the prepared dish. Chill in the refrigerator until it’s softly set but still tacky on top, about 45–60 minutes. It should hold the creamy layer without mixing.

Make the creamy layer. In a medium bowl, beat the softened cream cheese with the vanilla and a pinch of salt until smooth. Fold in the whipped topping until no streaks remain.

Add the creamy layer. Spoon dollops of the cream mixture over the set gelatin, then gently spread into an even layer. Work slowly so you don’t disturb the base.

Chill again. Refrigerate for 30 minutes to firm up the creamy layer.

Top layer (optional but pretty). If you want a glossy finish, prepare one more box of strawberry gelatin as directed on the package (use 1 cup boiling water + 1 cup cold water for a firmer set). Let it cool until just warm, then carefully pour over the creamy layer. Chill until completely set, 3–4 hours or overnight.

Serve. Slice with a sharp knife, wiping the blade between cuts. Use a flat spatula to lift clean squares.