Lime-Mint Ice Cream Bars

Heat oven to 350 degrees F. Line a 9- by 13-inch baking pan with nonstick foil, leaving a 3-inch overhang on two sides. In a food processor, process the cookies until finely ground. Add the butter and pulse until blended. Press the cookie mixture into the bottom of the prepared pan. Bake until golden brown, 8 to 10 minutes. Let cool completely, about 25 minutes. Using an electric mixer on high speed, beat the heavy cream, condensed milk, sour cream, and vanilla in a large bowl until thick, stiff peaks form, 3 to 5 minutes. Fold in the mint and lime zest. Spread the mixture over the cooled crust. Cover and freeze until firm, at least 8 hours and up to 2 weeks. When ready to serve, use the overhangs to transfer to a cutting board and cut into bars.