Let 1 (10-ounce) bag frozen strawberries sit at room temperature for 10 minutes to take the chill off, but do not thaw completely. Meanwhile, line an 8×8-inch baking pan (about 2 inches high) with 2 sheets of parchment paper, positioning them perpendicular to each other, so that the parchment hangs about 2 inches over all 4 sides of the pan to form a sling.

Process 1 (about 13-ounce) package vanilla sandwich cookies and 1/4 teaspoon of the kosher salt in a food processor until the cookies are the texture of sand, about 20 seconds. Add 6 tablespoons melted unsalted butter and pulse until combined, 6 to 8 (1-second) pulses. (Alternatively, place the cookies in a zip-top bag and smash with a rolling pin, then stir it together with the butter and salt.)

Transfer about half of the mixture (about 1 cup) to the baking pan. Use your fingers to press the crumbs into an even layer, making sure to reach the edges and fill the corners. Transfer the remaining crumbs to a small bowl. Wipe the food processor clean with a paper towel.

Process the strawberries in the food processor until broken into pea-size pieces, about 20 seconds.

Beat 1 cup cold heavy cream in a stand mixer with the whisk attachment on high speed until stiff peaks form, 2 to 3 minutes. Beat in the strawberries, 1/2 cup strawberry jam, and the remaining 1/4 teaspoon kosher salt on medium speed until well-combined, about 15 seconds, scraping the sides and bottom to make sure everything is incorporated.

Pour over the crust and spread into an even layer. Cover and freeze until the surface is firm to the touch but not frozen solid, about 3 hours.

Sprinkle the remaining cookie crumbs over the strawberry layer. Use your fingers to press the crumbs together and into the ice cream layer.

Cover and freeze until firm, at least 6 hours but preferably overnight. When ready to serve, grasp the excess parchment, lift the slab out, and place on a cutting board. Cut into 9 to 12 pieces.