Set the oven to 400°F and let it reach temperature before baking. A fully heated oven gives the crust its intended brief bake.

Toss the crushed pretzels with the melted butter and 3 tablespoons of sugar in a bowl. The pieces should look evenly coated, with no dry pockets underneath.

Pack the coated pretzels into an even layer across the bottom of a 9x13-inch pan. The corners should feel as compact as the center, without loose piles or bare spots.

Give the crust a 6-minute bake, then let the pan and crust cool completely to room temperature. Look for a buttery golden sheen and a lightly toasted aroma rather than deep browning.

Use a hand mixer to blend the cream cheese with the remaining 3/4 cup sugar until smooth. The mixture should look creamy rather than lumpy before the whipped topping goes in.

Use a spatula to fold the Cool Whip into the sweetened cream cheese, then cover the cooled crust with an even layer that meets every side and corner. A continuous band of filling against the pan helps keep the fruit topping away from the pretzels.

Place the pan in the refrigerator until the filling is thoroughly chilled. The surface should feel cool and hold its shape rather than slump or smear easily.

Stir both packages of strawberry Jell-O into the 2 cups boiling water until the granules disappear. The liquid should look uniformly colored, with no gritty sediment at the bottom.

Allow the dissolved gelatin to lose some heat before adding the fruit. The bowl should no longer feel piping hot.

Stir the frozen strawberries and crushed pineapple into the gelatin mixture. The fruit should spread throughout the liquid, and the cold berries will help cool it further.

Pour the fruit mixture gently across the chilled filling once the liquid reaches room temperature. The topping should remain fluid but feel neither hot nor noticeably warm.

Refrigerate the assembled pan overnight without disturbing the layers. The finished topping should hold a gentle jiggle without loose liquid sloshing across the surface.