In a medium bowl, stir together crackers, melted butter, and 3 tablespoons sugar. Firmly press mixture into bottom of a 13×9-inch baking dish. Bake for 10 minutes. Let cool completely.
In a large bowl, beat cream cheese and remaining ¾ cup sugar with a mixer at medium speed until smooth. Fold in whipped topping. Spread mixture onto cooled crust. Refrigerate until cold and set, about 2 hours.
In a medium bowl, stir together gelatin and 3 cups boiling water until dissolved. Refrigerate, stirring occasionally, until thickened and just beginning to set, 30 minutes to 1 hour.
Stir strawberries into gelatin mixture. Gently pour strawberry mixture onto cream cheese layer in pan. Refrigerate until strawberry mixture is cold and set, at least 4 hours or up to 1 day.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/lemon-strawberry-saltine-tart/