01 - In a large bowl, whisk together sweetened condensed milk, Greek yogurt, key lime juice, lime zest, vanilla, and a pinch of salt until smooth.
02 - In a separate chilled bowl, whip heavy cream using an electric mixer or whisk until stiff peaks form. Gently fold whipped cream into lime mixture until fully incorporated and smooth.
03 - Line a 9x9-inch pan with parchment paper. Pour in lime ice cream mixture and smooth the surface evenly. Freeze for at least 4 hours or until firm.
04 - Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
05 - In a mixing bowl, combine graham cracker crumbs, all-purpose flour, baking powder, and salt.
06 - In another bowl, beat unsalted butter and brown sugar until light and fluffy. Incorporate the egg and vanilla extract until homogenous.
07 - Gradually add dry ingredients to wet mixture, stirring just until combined. Do not overmix.
08 - Portion dough into 16 tablespoon-sized balls onto the prepared baking sheet, flatten each slightly. Bake for 8 to 10 minutes until golden. Transfer to a rack and cool completely.
09 - Once ice cream is fully set, use a round cookie cutter matching the cookie size to cut out 8 discs from the frozen ice cream.
10 - Place each ice cream disc between two graham cracker cookies. Serve immediately or wrap and freeze until ready to enjoy.