Preheat oven to 350°F.
Combine crushed pretzels, melted butter, and ½ cup sugar.
Press into a greased 9×13-inch baking dish.
Bake for 10 minutes.
Cool completely.
Beat cream cheese until smooth.
Add remaining 1 cup sugar and vanilla; mix until creamy.
Fold in whipped topping.
Spread over cooled crust, sealing to the edges.
Refrigerate while preparing topping.
Dissolve strawberry Jello in boiling water.
Cool until slightly thickened.
Stir in sliced strawberries.
Spoon over cream cheese layer.
Refrigerate at least 4 hours or overnight.
Slice and serve chilled.