01 - In a large bowl, whisk together the sweetened condensed milk, Greek yogurt, key lime juice, lime zest, vanilla extract, and a pinch of salt until fully blended.
02 - In a separate chilled bowl, whip the cold heavy cream until stiff peaks form. Gently fold the whipped cream into the lime mixture, combining until smooth.
03 - Line a 9x9-inch pan with parchment paper. Pour the ice cream mixture into the pan and smooth the surface. Freeze for a minimum of 4 hours, or until firm.
04 - Preheat the oven to 350°F. Line a baking sheet with parchment paper.
05 - In a bowl, combine graham cracker crumbs, all-purpose flour, baking powder, and salt.
06 - In a separate bowl, beat unsalted butter and brown sugar until light and fluffy. Add the egg and vanilla extract, blending until incorporated.
07 - Gradually incorporate the dry mixture into the wet ingredients, mixing just until combined. Scoop 16 tablespoon-sized dough portions onto the prepared baking sheet and flatten each slightly.
08 - Bake for 8–10 minutes until golden brown. Allow cookies to cool completely on a wire rack.
09 - Once the ice cream is frozen solid, use a round cookie cutter matching the cookie size to cut out eight ice cream discs.
10 - Place each ice cream disc between two graham cracker cookies. Serve immediately or wrap sandwiches individually and freeze until ready to enjoy.