Spray a 10-inch cast-iron skillet with baking spray with flour.
For crust: In a large bowl, toss together cracker crumbs, crushed pretzels, ¾ cup melted butter, and sugar until moistened. Add remaining 2 tablespoons melted butter, if necessary. Using the bottom of a measuring cup, press mixture into bottom and up sides of prepared skillet. Freeze for 15 minutes.
For filling: In a large bowl, beat cream cheese with a mixer at medium speed until creamy. Add confectioners’ sugar, lime juice, orange zest, orange juice, and 1 teaspoon lime zest, beating until combined. Fold in whipped topping. Spread filling into prepared crust. Sprinkle with remaining 1 teaspoon lime zest.
Loosely cover and freeze until firm, at least 6 hours. Thaw in refrigerator until softened, about 1 hour, or at room temperature for 30 minutes before serving. Garnish with pretzels, orange zest, and lime slices, if desired. Cut with a sharp knife dipped in hot water.
Recipe by Southern Cast Iron at https://www.southerncastiron.com/key-lime-icebox-pie/